I am attending a conference in early June and would appreciate recommendations for mainstream hotels close by the convention center...additionally, any suggestions for close by eateries and historical sites.

My favorite NO restaurant is right by the convention center (intersection of Julia & S. Peters St.):
http://www.riomarseafood.com/
Worth more than one visit.

I always stay in the FQ (a nice 20 minute walk from the Convention Center along the waterfront), but there are many, MANY mainstream hotels right around the Convention Center:

http://www.marriott.com/hotels/trave...ention-center/ (low range for the area)

http://www.marriott.com/hotels/trave...vention-Center (mid-range for the area)

http://therooseveltneworleans.com/ (upper range for the area)

There are 1 or 2 hotels actually attached to the convention center, a Marriott on Canal Street and a bunch in the FQ. Just be very sure that you are in a safe area (going even one block in the wrong direction can take you into a very high crime area that is not safe day or night.) We stayed once at the Ritz Carlton and they had armed guards at the doors in the ground floor lobby. they told us from the front of the hotel we could only go left - not right - or risk being in an unsafe area. The hotels attached to the convention center are convenient further from risky areas.

New Orleans is just as safe as any large U. S. city and just as safe as NYC. There are areas of high crime but tourists do not frequent those areas. The CBD including the Convention Center is very safe in the day and early evening. I would take a cab late at night in any area of NOLA. I have stayed at the Ritz Carlton in NOLA about 15/20 times and never saw an armed guard. I walk 4 miles a day and I always went to the right on Canal and walked from Canal to Esplanade on Rampart in the daytime though. I then walked to the river and back W to the CBD. I have never witnessed any crime in NOLA and I have been going for over 40 years. Come and enjoy the city.

Here's some very nice hotels near the CC. Enjoy your visit.

Hampton Inn and Suites Convention Center @ 1201 Convention Center Blvd., New Orleans, LA 504 - 566 - 9990.
http://www.hamptoninn.com/en/hp/hote...tyhocn=MSYLAHX
Courtyard New Orleans Downtown Convention Center @ 300 Julia Street, New Orleans, LA 504 - 598 - 9898.
http://www.marriott.com/hotels/trave...ention-center/
Embassy Suites New Orleans Convention Center @ 315 Julia Street, New Orleans, LA 504 - 525 - 1993.
http://embassysuites1.hilton.com/en_...siana/index.do
New Orleans Marriott at the Convention Center, 859 Convention Center Boulevard, New Orleans, LA 800 – 305 – 6342.
http://www.marriott.com/hotels/trave...ention-center/
Wyndham Riverfront Hotel @ 701 Convention Center Blvd., New Orleans, LA 504 - 524 - 8200.
http://www.wyndham.com/hotels/MSYRF/main.wnt
There are great restaurants in the CBD and FQ. You can take the Riverfront Streetcar to the FQ from the CC. Emeril's is my favorite restaurant in the WHD in NOLA. They have a 3 course prix fixe lunch for $19.50 Monday/Friday. Dinner is outstanding. Feast is a new restaurant that just opened. Herbsaint and Iris are great fine dining restaurants in the CBD. Le Foret is a romantic fine dining choice for dinner. Tommy's is a block from Emeril's and serves outstanding classic creole Italian cuisine.
Emeril's @ 800 Tchoupitoulas St., New Orleans, LA. 504 - 528 - 9393.
http://www.emerils.com/restaurant/1/...s-New-Orleans/
Feast Restaurant @ 200 Julia Street, New Orleans, LA 504 - 304 - 6318.
https://sites.google.com/site/feastneworleans/
Herbsaint @ 701 Saint Charles Ave., New Orleans, LA. 504 - 524 - 4114.
http://www.herbsaint.com/
Iris @ 321 North Peters St., New Orleans, LA. 504 - 299 - 3944.
http://www.irisneworleans.com/
Le Foret @ 129 Camp St., New Orleans, LA 504 - 553 - 6738.
http://www.dmillanleforet.com/
Tommy's Cuisine @ 746 Tchoupitoulas St., New Orleans, LA. 504 - 581 - 1103.
Bon Ton is outstanding creole cuisine. There are numerous lunch and dinner special's in NOLA. Mr. B's has a 2 course prix fixe lunch for $20.00. Domenica is a casual John Besh Italian restaurant in the Roosevelot Hotel a block from Canal Street. They have happy hour specials from 3/6 half price pizza and drinks. Dining at the bar at Domenica is fun. Luke is another John Besh restaurant in the Hilton on St. Charles. They have a 2 course express lunch for $15.00 and 3/6 Happy Hour half price drinks and 50 cent oysters. Dining at the bar at Luke is fun also. Antoine's is in the FQ and they have a prix fixe 3 course lunch for $20.00.
Domenica @ 123 Baronne St., New Orleans, LA. 504 - 648 - 6020.
http://www.domenicarestaurant.com/
Luke Restaurant @ 333 St. Charles Ave., New Orleans, LA. 504 - 378 - 2840.
http://www.lukeneworleans.com/

I've stayed at many of the highrise hotels next to the convention center, but I agree with the advice to stay in the French Quarter if you can. It would be a walk back and forth, but it's a nice walk in NOLA and IMO it's much nicer to stay in the French Quarter instead of high rise hotel. My favorite hotel is the Dauphine Orleans but there are many others that would be good as well.

I second Starrs.Stay in the FQ and walk to all the great places to visit. Stay at Le Marais, Monteleone, Provincial, St. Marie, Place D Armes, Iberville Suites or Dauphine Orleans.
Hotel Le Marais @ 717 Conti Street, New Orleans, LA 504 - 525 - 2300.
http://www.hotellemarais.com/
Hotel Monteleone @ 214 Royal Street, New Orleans, LA 504 - 523 - 3341.
http://hotelmonteleone.com/
Hotel Provincial @ 1024 Chartres Street, New Orleans, LA 504 - 581 - 4995.
http://www.hotelprovincial.com/
Hotel St. Marie @ 827 Toulouse Street, New Orleans, LA 504 - 561-8951.
http://www.hotelstmarie.com/
Place D'Armes Hotel @ 625 Saint Ann Street, New Orleans, LA 504 - 524 - 4531.
http://www.placedarmes.com/
Iberville Suites Hotel @ 910 Iberville St., New Orleans, LA 866 - 229 - 4351.
http://www.ibervillesuites.com/
Dauphine Orleans @ 415 Dauphine Street, New Orleans, LA 504 - 586 - 1800.
http://www.dauphineorleans.com/

I don't agree that New Orleans is "just as safe as any large U.S. city." New Orleans' violent crime rate is 25% higher than that of New York. However, it's also lower than those of St. Louis, Boston, Miami, Las Vegas, Atlanta, Houston, Tulsa and Oklahoma City, among others, all places that most of us wouldn't really think of avoiding because of crime. I think that, compared to some other cities, New Orleans has some dangerous neighborhoods that are relatively close to the tourist areas. And it would indeed be a poor choice to turn right rather than left on Canal after walking out of the Ritz Carlton. I pay attention to where I'm walking in New Orleans, but I don't let worries about crime disrupt my frequent visits there. It's an amazing place.

I'd say the location of lodging should depend on how much time you're planning to actually spend at the meeting, and how often you plan to walk back and forth to your hotel room. It might make sense to pick a place that's in or next to the FQ, but closer to the river, so that you could get the best of both worlds. From the Ritz, for example, it would be a long walk to the Convention Center. At night, I think you'll prefer not having to walk any farther uptown than Poydras Street to get back to your room.

I've stayed at the Hilton and it was fine - nice hotel, standard Hilton in terms of amenities, service, etc.

A great place to eat breakfast or lunch located not too far from the Convention Center is Red Gravy Cafe:

http://www.redgravycafe.com/

Hawksbill is right about the safety issue re NOLA, which is a little unusual in my travel experience. Boston may perhaps have more crime than NOLA, but if so, it will be concentrated mostly in places away from tourist areas. NOLA's bad parts of town are scattered (sometimes within isolated blocks), can change quickly to bad from good, and some (like the area immediately northwest of the FQ) border tourist areas. Unfortunately, it's easier for an unsuspecting tourist to mistakenly wander into NOLA's Iberville Projects than into Boston's Orchard Park Projects in Roxbury. And some of NOLA's cemeteries (the best being worthy tourist attractions) have notable safety issues unless you go as part of a tour.

It's a good idea to do some homework on areas to avoid in NOLA (asking at the hotel desk also isn't a bad idea) and then to take the usual urban precautions.