Hey, i'm a drummer and am looking for an instrument to help me learn to read different pitches better. I read rythms just fine and play pitches just fine by ear, but i'm supposed to learn how to play mallets. Help?

If you don't know the piano, I suggest you start that.

just like the person said before me, you should start on piano. Aside from being a beautiful instrument it can also teach you many things about music and theory

perhaps the alto sax or piano would be appropriate, good luck!
i personally prefer the tenor saxophone and the clarinet. The bassoon is great, but hard to learn, and expensive!

Piano all the way,but if not try tubular bells.

In my opinion, I think the all percussionist should have some piano experience. It gives you the knowledge to read both treble and bass clef. Piano also is a good start of where to learn scales. It should also help you match up the notes on the page to where they are on the keyboard. If you need any other help or need me to explain something better, you can message me. I have been playing piano for 10 years and percussion for 4. I love to play all percussion instruments, but I am strongest at mallets.