Tune ups ain't what they use to be! A tune-up, per se, on your car is typically plug change. I can't think of anything else of a "tune up" nature that will go 100k miles.
The plugs are not difficult to change. The fronts are a piece of cake. The rear ones are a little tougher. The two on the passenger side can be reached with the left hand. The one on the right can be reached with the right hand. The toughest part on the rear is breaking the boots free from the plugs if they've never been off. This takes some real finger torgue and wrist leverage but I can do it and I'm average build and height. When you reinstall the plug boots use a little silicone grease on the inside tips of the boots. This will significantly help ease your pain the next time you do plug work.
It is funny that GM recommends plug changes at 100k. I thought that was only for Platinum. The originals I pulled off looked like NGK Copper, each with a funny little tit on the ground electrode.
It misfired like crazy with new Platinums. I have always used Platinums but a few on this site said they were not compatible with the 2000+ SC. I really did not believe until I went back to copper cores. Sure enough..........no more misfires.
2001 SSEi- black; stock 92K
1995 Vette; Competition Yellow; stock; 38K