Tikal isn't just a few temples or pyramids, it is the name of the once thriving city. An old world metropolis. And it is really an amalgamation of buildings covering more than 100 square Kilometers. Huge.
Fortunately the main section can be visited in a day. The center has two huge temples on either side with a great selection of ruins scattered about. There are even a few stellae left (large rock carvings denoting important events in the mayan calendar).
You can climb one of these temples, and I recommend it highly. The view alone is worth it. At the top you are just above the jungle canopy, and can see for many miles in every direction. Popping up here and there are other temples. The wildlife is rampant. Howler monkeys screech and bellow, flocks of parrots and toucans fly by, coatamundi's rummage through your bags (trust me, they will) and all this filled in by insects too.
And if you're early enough, you can see the mist rising off the jungle to reveal a beautiful sunrise. But to see this from atop a temple that was used for human sacrifices 1,000 years ago, it makes ones spine tingle. The effect is electrifying.
Then set off for a day of exploring. The site, as mentioned, is vast, but truly rewarding.