There are tons of groups to ride with. One group and route that really strikes me for your area is the Come Ride With Us! Group. They have 3 monthly rides that start near you.

Lake Houston Out N Back - 45 miles
http://www.meetup.com/Come-Ride-With...nts/223286057/

The Road West - 44 miles
http://www.meetup.com/Come-Ride-With...nts/223286092/

Urban Bridges Ride - 30 miles
http://www.meetup.com/Come-Ride-With...nts/223286118/


That is a good group to join. There is varying skill level and they are very helpful and positive. I recommend these type of rides to learn your basic group riding skills before you go do a bike shop ride.

You can also join my group. We are small with generally 3 or 4 of us. But we ride outside of Houston mostly. Pearland on Sunday.

Pearland Ride - 43 miles
http://www.meetup.com/Make-Shift-Hap...nts/223412855/


Tons of rides listed on:
www.Texbiker.net
Upcoming Rides - Bike Barn - Houston, Texas:
https://www.google.com/#q=Houston+area+cycling