1999 and older-great price-
I'm a very new-2 month-Suburban owner(2wd 1998 196,000 miles-$2950).I've been very pleasantly surprised with it.The PO had the trans rebuilt at 186000-ac & intake mani gasket 155000.It runs just fine-motor strong, not obvious oil use in 600 miles-.It does rattle a bit on our washboard roads, but it is pretty quiet on decent roads and highways.
The mpg isn't bad-12 mpg in pure short trip city driving.If I drive across town-with a mix of driving on city interstate and ground streets -I get 16 mpg-not bad at all.My much newer designed and 500 lb heavier Titan only got .2mpg better on the same drive.
I would rather have the newer motor and body style of course-and the better brakes of the 2000 on up, but the 1999 and older are really selling cheap-because of $3 gas I guess.
If $$ is a concern-it was with me-a 1999 or older will sell for maybe $4000-$5000 less than a 2000 or newer with the same miles.
Luck,
Charlie