Can anyone recommend some popular and good restaurants in the hamptons (East, West, Sag Harbor, Amagansett, Montauk)? I'm in my late 30's so don't want young, rowdy, but like trendy, great food, good energy, hotspots...
Any advice is appreciated.

Nick and Tony's is in East Hampton and is always very good. It's tough to get a reservation. You have to call a certain number of days ahead. Check with them and mark your calendar to call and then sit on hold. It's casual and you may spot a celebrity or too. Order some zucchini chips to start.

make that or 'two.'

In East Hampton:

Nick and Tonis
Della Demina
Rowdy Hall (prob the msot affordable)

I think Rhea had a typo - should be Della Femina.

Exactly - as n Jerry della Femina - the advertising guru.

mea culpa - you're both right....maybe because I am not
a fan of his but had to put it out there.

Southampton- Red Bar, Savanna's
Sag Harbor- Sen (Japanese), Tutto il Giorno, the Beacon and there's a new place on Main st. in the old Spinnaker restaurant. American Hotel is very nice.
East Hampton - Cittanuova, Blue Parrot (Mexican), Turtle Crossing (bbq), East Hampton Point, new restaurant at the Maidstone Inn
Amagansett - Mezzaluna is opening

American Hotel-Sag harbor
Tratta's-Watermill-Trendy crowd and has a bar scene
Nick and Toni's
Palm -Eeast hampton
The laundry-East Hampton

Plaza Cafe-Southampton
75 MainSt.-Southampton

This is exactly what I was looking for. Thanks so much!
How about a b&b on or close to the water that's (don't laugh) not too expensive, but clean, charming, and...beachy?
Anywhere from Southampton to Montauk?

I usually stay with friends, but am staying at East Hampton House one weekend in August. It is part of Dune Resorts (see link below). I haven't seen it, but another friend has and said it is fine. Nothing is inexpensive during the summer, especially if it is clean.

http://www.duneresorts.com/default.asp?

There may be less expensive motels in Montauk.

Fortunately (unfortunately?) this year due to the economic climate there are quite a few "deals" to be had in the Hamptons. A friend recently booked a room at the Southampton Inn for under $200/nt.

What's not too expensive? Many of these restaurants are very expensive. You never stipulated on price.