Agree that Maidu is a very nice park, as is the Sac Complex. Over-all, I too like Arnaiz but those foul balls are a killer (no joke!). Hopefully the whole netting issue gets resolved - I'm surprised someone hasn't filed suit over it... If you need warmup facilities there, what about the large area kitty-corner to the whole park, across from the parking lot? The burritos and the floats make it all worth-while!
Other nice parks in Sac include Lonetree in Rocklin and Foskett in Lincoln. Both need a few more years for the shade trees to grow, but the facilities are nice.
Twin Creeks in Sunnyvale used to be beautiful, but it's been many years since I've been there. It's sinking now???! Niiiiiiiiiice...