Mariner's start selling Spring Tixs on January 7th. If you are wanting to see the Cubs or Giants there I would buy tixs than as these will go fast. For weekday games I can usually buy at face value from a scalper on the parking lot. Just be careful about what you are buying. Fakes happen.
Also the M's charge for parking now and have for the last few years.
The food @ Peoria isn't bad but I have not been overly enamored of the food selection in the Brewer's park (beer here too is limited) and at the Dodger's park.
We hit the Salt River park several times and I thought the food here was quite good.
Also even on a busy day I have often walked up to the ticket office and asked for the best available tixs and found myself down in the first or second row behind Home Plate.
Look at where you want to stay and make a rez soon. If the weather in the north gets white and cold rooms can be scarce...
Lastly: Bring sunscreen!