Mohegan is classier. Although I don't gamble much I play bingo at Foxwoods. Mohegan doesn't have bingo.
All my friends that gamble prefer Mohegan. You could actually go to both because they are a short drive from each other. Foxwoods has lots of stores and money people bring there kids with them to shop. It is much like a shopping mall.The best place to spend the least amount of money is the Keno lounge.
Both places have concerts and Mohegan now has a pro womens basketball team.
There are non-smoking sections at both.
The best place to go from there and spend a night would be Newport RI. Make sure you do the Cliff Walk.

I have to second the vote for Mohegan and agree the it is far classier then Foxwoods. They also have great restaurants owned by top named chefs.

The Sunner Shack Jasper White
Tuscany Todd English
Rain Chef frm French Laundry
Michael Jordans Steak House

Just to name a few...Also large no smoking section, great hotel and pool, spa, Comedy club and great acts for free in the lounge. Check out the website, we have been to both many times as we live in Connecticut , Mohegan is just more fun

As a follow-on, I, too, prefer Mohegan Sun - several sections are a bit newer, with a row of shops and restaurants connecting the Casino of the Earth and the Casino of the Sky. I would second the other fodorite's suggestion and be sure to check out each casino's websites to find out what shows, services, etc. are available - I know they both have their own spas, for example. In the area there's actually quite a bit to do - if you go to see Foxwoods, they have an excellent museum nearby (The Mashantucket Pequot Museum) that is a multi-million dollar interactive museum - very impressive. In addition, if you're into military/engineering history, I would recommend a stop at the US Submarine Force Museum in Groton at the Subase, where you can tour the first nuclear submarine Nautilis for free. And you could always do the touristy things in Mystic or wander around Stonington Borough if the noise of the slots starts getting to you! Have fun!

I also prefer Mohegan Sun by a mile. The hotel and shopping areas are newer and nicer, and the newest casino there, Casino of the Sky, is so open and well ventilated that smoke is not a problem there, even in the smoking area. (and I hate smoke!) They are close enough--10 minutes apart--so that you can go to Foxwoods too if you want to check it out. If you want to stay at Mohegan for 2 nights, the next morning you can still drive to another area, say, Mystic, where you can tour Mystic Seaport and/or Mystic Aquarium. There's lots of things to do in the area; depends on what you like.

Have fun and good luck.

FYI, Mohegan is closing their poker room next week.

Having lived right near the casinos for while, I agree with the others - the Mohegan Sun is much nicer. It's more Vegas-like and has better restaurants (thought the Bistro at Foxwoods is very good). Regardless, they are 7 miles apart, so you can visit both.

As for other activities, both have concerts, caberets, shopping, etc. But both are a stone's throw from Mystic and other areas of interest on the shore, such as Watch Hill in Westerly or Stonington Village. The Mystic area has two visitor's bureaus that can provide you with plenty of options (one is Mystic and More!).