Since you're new here, it would help if you mentioned what sort of price range you had in mind.
I'd say that three lights would be a good minimum.
Keychain light, main light, and a back-up for your main light.
Here are a few good choices. I'll stick with AA or AAA lights for now. Keychain: Fenix E01, iTP A3 EOS, Fenix E05. All are single AAA lights. The E01 puts out a very small amount of light, and the beam profile is less than ideal. But the runtime is excellent, and the light is very tough and reliable. The E05 is shorter, but puts out quite a bit more light compared to the E01. The A3 is the current AAA king of keychain lights. Does a variety of things well. Only slight downside is that it's not as tough compared to the E01. With the A3, you get three output levels. High mode is very impressive for such a short light. Price is very good as well, considering that its output can function as a full-sized flashlight if needed.
For a main light, there are a variety of good 2AA choices. There's the Mini-M@glite LED model, Fenix E21, Fenix LD20, 4Sevens Quark 2AA model.
For a back-up light, a single AA model would be a good choice. There's the Fenix LD10, 4Sevens Quark AA model, and the Energizer AA model. (The last one is particularly good if you're on a tight budget. Easily found at Target, the tailcap switch on the Energizer is rather soft. But that's the biggest disadvantage. Output won't be as bright as the two other lights, but the price is very low with better than decent quality.)
Hope this helped.