A few hills to start with but flat thereafter.
http://www.mapmyride.com/routes/fullscreen/133690473/
Naas > Mullacash > Ballymore > Bishopscourt > Blessington > Crosschapel Hill > Rathmore > Kilteel > Rathcoole > Newcastle > Celbridge > Taghadoe > Kilcock > Clane Road > Right at Boherhole > Prosperous > Kilmeague > Allen Cross > Blacktrench > Naas.
Autumnal, social, steady spin, ideal for those new to or returning to B Group level. About 27kph, regroup when necessary.