Crawfish in Clear Lake
Boondoggles has crawfish for $5.95/lb on Thursday nights. Crawfish is not my thing so I haven't tried them but the place packs out. They also offer complimentary popcorn with seasoning that is addictive you just have to ask for it. Allot of beers on tap.
I loved Sonny's too. Miss it greatly. Try Floyd's on I-45 at Nasa 1, I think you'll find it a very good replacement.
Floyd's is a bit far for me to go unless I'm going to the mall or somewhere else down there so I usually eat them at Willie's and have found them decent.
I don't think they have boiled crawfish but they have other great seafood items - try Little Daddy's Gumbo Bar in League City.
I've gone cheap the last year or so and do them myself. Whatever your favorite seafood market is in Seabrook will have them at less than half price of a restaraunt. Get some decent bread and beverage of choice and your in business. If you want some boiling tips let me know. One hint, your water isn't ready unless you're sneezing, a lot.