as far as the car i got my 98 bonnie (same engine and trans) a few years old and has been the best car for reliability ive had. aside from doing the intake manifold once when it was young and once again a couple months ago its been rock solid and has about 180k on it. the wife drives it daily and i dont feel like she could have anything more safe or reliable in buying a new car. she doesnt like anything they make any more anyway.
so if you intend on keeping it replace all the vacuum lines you wont be sorry unless you dont. the solenoids dont go very often, people just replace them with out testing them for some reason but its a waste of money.
1998 Bonneville SSE
2007 Monte Carlo LT-KYB, Clarion, Polk audio, Kicker
1999 Yukon SLE-KYB, Air lift, Reese dual-cam, Tekonsha
1987 Firebird-355/th400-nothing stock