The arboretum is about 50 miles out of Phoenix, and it's easy walking, with an uphill loop with good footing. Probably my favorite place in Arizona. There's a lake, so birds are plenty.
South Mountain is a hiking trail with rocks and boulders. I suggest driving up the mountain and hiking from the parking lot. I haven't hiked up from the bottom in quite a while. It can be pretty difficult in places. There's no water nearby the trail I'm thinking of, so not a great birding spot.