I use Boeshield T-9 on the chain every couple hundered miles unless I've been in the rain. Also a drop on the brake pivots, deraileur pivots and shifter/brake cables. I degrease the chain and clean it about every 500 miles. About every 1000 miles a major tune up at the LBS to true up wheels and tighten spokes keeps things working nicely. The LBS also checks any items for major wear. Small things like tires, chain keepers (used on a recumbent), and brake pads I do myself. Granted I could probably do the whole thing myself with some additional tools but I really don't feel like tearing a bike apart and putting it back together when I could be riding or doing something else. Flats I repair myself.
'bent Brian