It always depends on your interests. IMHO I find Lima downtown a must, specially if you like culture, architecture and history. It's a Unesco World Heritage, and has lot of interesting sites, some already mentioned (Cathedral, San Francisco Catacombs, Museum of Inquisition (a museum not so popular but very very interesting, it shows the dark times of the colony and catholic religion).

A restaurant is a must. Yes, peruvian seafood is very rich. I hope you like our cebiche (ceviche, seviche, nobody knows). Cebiche is a latin american food, it's not exclusively peruvian, but we peruvians claim our is the best of course.

Miraflores (my neighborhood and Barranco are another musts. I recommend Barranco by night, specially the walk around Puente de los suspiros (Sighs Bridge).

If you want a folk night show, Brisas del Titicaca is an option. Food is not that great but the show is very good.

I read rajuabju enjoys the Water Circuit, though it's a tourist trap. That confirms my idea that tourist traps is something relative. Larcomar or Brisas may be considered also tourist traps. But it's a place to relax and if you enjoyed, that's good.

Lima suffers of heavy traffic, that gives a bad perception sometimes. But it has its jewels, like Bangkok or any crowded city. You will enjoy it.

Your hotel is well located, too