What makes them sound good?

What do YOU mean by "full?"

How many microphones? And what is mic'ed?

I'll go ahead and make suggestions...

Using the mics, find the spot that sounds the best, and mix, EQ, compress, and pan to taste.

Not sounding full can usually be corrected by EQ. However, if it doesn't sound "right" going in, it typically won't sound right coming out...

Recording live drums is difficult. Even with the same player and kit... Keep working at it until you find what you like. Try not to judge the recorded drums until you hear it in the mix. What sounds great "solo," can sound bad in the mix - and visa versa.

before you hit record you need to check phase of each channel. unless you have just one drum mic phase will be a consideration. i'm not an expert yet. When your doing the setup, start w/ kick/snare. If you have mics inside/out on the kick, use the phase flip function to hear the the difference between a thin sound, and the other (which hopfully is huge, well tuned, and has new skins!). Next is the snare if you mic top/bottom keep your bottom mic out of phase from the top. If i were better at the art of drum miking i'd be able to tell you more, but most of what i know is phase flip, listen for 'bigger, fuller, better, as good... thinner, weaker, shallow.' You want full..., phase has a way of filling, or easily as thinning. that's why it usually takes about two/+ hours to mic a new kit at my studio. Room mics can make drums sound huge, the guys i work for pick a place and face the mics right at the wall like an inch away, seems they want to get those reflections, and well, it works so far, it makes drums sound huge. Useful instead of a verb pluggin. But the room has variable acoustics, and was pretty well designed/built.
Your room, mics, console, pre's make a big difference man, but check your phase, it's been most handy for my current drum stuff. Tuning is just as inmportant, as the new heads.
I'd really welcome all the drum micing advice i can get, cuz i'm not solid yet.

Hi... I use Drumagog. So I use one mic for each drum and cymbal. The drum sounds are excellent. What I meant by " Full" was kind of like how you can record one guitar track and the tone sounds good but the over all sound sounds kind of empty. Once you get like three to four different tracks, it sounds really full. Did you understand that? But obviously you can't do that with drums. I don't have any room mics. Should I bus all the drums to one track and ad some reverb or something to use in place of room mics? Thanks for the tips by the way! Very helpful. God bless!

On the rare occasion that I am dealing with samples only and I need a natural "full" sounding kit I send the tracks to a P.A. in my live room and mic that. Re-amping this way gives the kit some realism that digital verbs just can't. I will often use digital reverb as well.