I live in the N E valley (Las Sendas / Mesa). Right next to Bush Hwy (to get to Saguaro) and Usery Mountain range. I ride out here daily. Depending on how much "flat" riding you want to do there is plenty of areas out here to ride. Bush Highway (CAT5 and CAT3 climb), BeeLine Highway, Shea Rd, Usery (repeats, its a CAT3 climb). I can leave my house and ride into Fountain Hills, Scottsdale area without hitting many traffic lights. A typical pre-work morning ride out here is 25-30 miles and 1200 ft of climbing so nothing crazy at all. You can really rack in the miles up in North Scottsdale area (Bartlett especially). Pretty much any where you go in the PHX area is only a few minute (mesa to phx - 20 minutes / mesa to north scottsdale 30 minutes) drive to get any where else to go out and ride. Just depending on the area you want to be in.

Everything down South East where I have ridden (Queen Creek, Chandler, Gilbert) has been pretty flat.