Lipitor may be the cause or be abetting the minor elevations in the liver function tests. These elevations you report are fairly trivial in the scheme of liver disease. When I worked at a plasma bank as a screener the Feds put in a strict upper limit on the AST of 40 as a proxy for the then unavailable hepatitis C test. It knocked about 5% of the donors off the rolls. Most of the elevations were related to 6pk a day habits common in the clientele. Since you were extremely overweight in the past you likely have some degree of fatty liver disease (no big deal) and if there is any background of alcohol in your younger days the liver would also have taken some hits, again no big deal, but the combo may well account for the LFT variances. If your lipitor dose is 10-20mg occasional LFT checks at 6mo intervals are in order. If you are on 40-80mg dosages more frequent ones for awhile to see if there is any trend. If the LFTs don't change over a year or two then any concern should be relieved. Plavix is a kind of big gun to use unless you have a stent somewhere or already had a cerebral, anginal or infarctional cardiac event or have major peripheral vascular disease. The peripheral vascular dz scenario is unlikely with your biking success. Plavix adds 20-30% to aspirin's platelet aggregation inhibition at most and at $5/day, even if someone else is paying for it, is a lot of $ for small gains in the absence of a stent.
I see a fair number of little old ladies (LOL) with huge hematomas from minor falls that are secondary to their plavix. Aspirin in 81mg doses gives you 80% of the platelet inhibition needed for prevention purposes for potential cardiac and cerebral disease.
If you already have HAD such an event then plavix is in order, if not....
Steve