The last LA was commissioned in 1996. 3 Seawolfs were commissioned between 1997 and 2005; they proved to be too expensive.
17 Virginia's have been commissioned since 2004, with 11 more in various stages of building plus this 10. This newest order will be Block V boats.
Yes they are much better boats. A good open source statement is "The Virginia class incorporates several innovations not found in previous US submarine classes" from Wikipedia, which has a summation of the open source improvements.
One item of discussion is their size. In order to accommodate the Tomahawk land attack capability makes them larger than they otherwise might be. At the open source level that leads to a discussion of whether a smaller, cheaper SSN optimized as a hunter killer would be useful.
A lot of the technology in the Virginia's is being reused in the Ohio SSBN replacement, the Columbia Class. In turn, there is cooperation with the RN for the Vanguard SSBN replacement, the Dreadnought Class. I'm not aware that there was as much collaboration between the Virginia and Astute Classes.
Edit: oops, I incorrect said they were all built by Electric Boat. That's incorrect, half were built by Newport News. Guess my corporate pride got the best of me...
