They are on different sides of the valley but Marriott Mesa is very close to cubs stadium. From there Maryvale which is where the brewers play is about an hour drive . The rates do go up during spring training . Also look at the teams road games as cubs sell out at home . Tempes marriott in Buttes is close to Angels stadium and that might work to see your teams on the road
There is also an excellent Marriott Courtyard in Scottsdale Salt River, easy access to the 101 Freeway and quick shot south to that ballpark. It is also convenient to restaurants at the next exit north from there and also to get to Old Town Scottsdale for even more restaurants and night life choices.