I also got to see an A10 during an airshow in Klagenfurt, Austria. I took a picture of the GAU8 and it still looks awesome on the small photograph.
As for CAS - the USAF tried to modify the F16 for CAS by adding the GPU5 pod IIRC. It contains a GAU13, the sweet little four barreled sister of the GAU8. They both use the same ammo, but since the weapon was pod mounted accuracy was as good as non-existing, and since not much ammo was carried(350rds or so) cluster bombs proved more effective.
In short terms, yep the A10 is about the only dedicated CAS aircraft in the AF.
Oh, and the A10 was nor really a replacement for the A1. In fact the A1 had been put out of service before the Vietnam war, but was in service again because F4s and F105s proved too inaccurate for CAS and couldn't stay over the target long enough. The A1 could and carried much ordonance, including bombs, napalm and four 20mm cannons. It was accurate due to it's low speed and could circle quite a while over the own troops and support them.
In every single book about Vietnam I read, A1s were said to be the best and most liked CAS fixed-wing aircraft. Downed pilots, SOG members as well as chopper pilots and normal troopers liked them, because they usually provided best air cover.
Snakeye