We've stayed twice in units at 1800 Atlantic. Not too close to Duval Street, but really nice pool and ocean location.
"Offical" website is www.1800atlantic.com, but do a search and you'll find other rentable units through different parties.
Here's one that gives a picture of the pool with ocean behind it.
http://keywest.com/a1beach.html

My husband and I stay at the Galleon a couple of times a year and love it. It's in a wonderful location on the Gulf within close walking distance to lots of restaurants, tourist activities and the sunset celebration. The units have recently been redecorated and the kitchens are fully equipped (including a washing machine and dryer). Check out their website at galleonresort.com

How can you be assured that a company or an individual renting a condo/house in Key West is honest? There are some condos for rent during our stay in early May that would be less expensive than our guesthouse for 4 adults. Many condo owners want 50% down to hold that property and I am uncomfortable sending that much money to someone that I don't know.

Laurie - is this person asking for 50% down in cash or check? We found a great deal on a condo, but they would only accept a personal check. That put up red flags for me. At least when you use a credit card, you have the protection of that. But if you have problems, and you paid with a check, what are the chances you'll get all your money back. Probably slim. But if you check around, maybe with the BBB and the place does accept credit cards, you'd probably be okay.

I can understand why someone might be reluctant to rent a condo from an individual without having any advance notice of what it's like. The Galleon is a timeshare that rents to non-owners and is managed on the premises. The units are identical, so you you know exactly what you're getting. They do require a 40% deposit that will be fully refunded if you cancel more than 30 days of your expected occupancy. Key West has recently passed a law forbiding short term (anything less than a month) rentals by anyone who isn't licensed. Apparently this is causing lots of trouble for people who bought property with the express purpose of renting it out. I think I'd be a little reluctant to rent from an individual who isn't licensed until they get all the details worked out about the new law. You might consider going through one of the rental agencies. At least you'd have someone to blame if things didn't work out as expected!

I think that Harbour Place condos in Truman Annex are just beautiful. They have a view of the harbor -- which means sunset views from your terrace or balcony. Also, during the day you can see the cruise ships come in and out of port. A number of real estate egencies right in Key West have listings for these units -- namely At Home In Key West, Inc. or Compass Realty. Good luck and let us know how you make out.