Push-ups are nice and can give you a good pump, but if you have decent levels of strength, they aren't going to make you stronger (unless you do one-arm pushups). Pull-ups work fantastic for a longer period of time since you are moving more of your bodyweight, but eventually you'll want to add weight.
At the same time, I'd want to make sure you do some rowing movements, rotator cuff work and upper back/rear delt work because all those push-ups and pull-ups are going to be murder on your shoulders if you don't.
Also, I wouldn't rely on them exclusively for a workout.
I recently purchased the Upper Body Blast Straps from Elitefts.com. They are awesome! Not only do they make push-ups much better (working stabilizer muscles), but you can do a variety of other exercises (rows, chins, dips, ab fallouts, curls, rear delt flyes, pec flyes, etc.
They come in handy for some of the exercises I use during my Westside template.