If you want to ride the MUPs, all the bike shops in town have free maps. There are a lot of MUPs but they are more fun for transportation through town than actually going for a ride. They are also kind of convoluted, so be willing to be lost. Remember, the mountains are on the West. The Boulder Creek Path downtown gets very crowded on weekends.
Here are a couple of simple, flat-ish road rides. You can pretty much pick a road in the area between Boulder and Longmont, and it will be good. Neva-Niwot road will be under construction for a few weeks, it's still paved right now but they are going to resurface it. There are services in Hygiene, but not at Eldorado Springs.
-- the southern 'spur' of this route from Baseline & Cherryvale to Eldorado Springs is the really nice part. You can return to town on the west side of town on bike paths, but it's too complicated to try to map. On the north loop, Valmont road is good too, but stay off Arapahoe.
Here is a moderate climb - you can start this one from the intersection of Hwy 36 and Lefthand Canyon if you want less riding. This ride is beautiful. There is a cafe at Jamestown, where you can get water and purchase baked goods.