i play classic rock/alt country. I already have an OD pedal. Really have no interest in playing leads.

What other pedals would you recommend for rhythm guitar?

I play a MIM Tele into Champion 600.
To me, any guitar without at least a hint of reverb sounds quite terrible. I'd also consider getting a chorus and delay like lyonk55 said, especially for clean sounds they can do so much for your tone.
chorus,reverb,delay AND flanger is gd if u wanna add a lil twist to your songs etc.
You should check out the Electro-Harmonix Graphic-Fuzz Pedal. Beutiful fuzz, reverb, and overdrive if you need it. Plus you can mess around and experiment with it forever to get that perfect tone.
I'd get reverb. Reverb, IMO, is the best effect in the world and probably the only one I couldn't play without. A hint of reverb gives your tone a huge amount of depth and sparkle. And I use a tele/fender amp rig too.
So today I went and got a Holy Grail Reverb and that was the ticket. I am havin some fun now.

MIM Tele > Boss BD2 > Holy Grail > Fender Champion 600.

I have found a couple combos that my ears lie. I am a smilin 40yr old.