We have been going to Spring Training every year since 2005. Here are some thoughts and tips in no particular order.
Think about going for a week and renting a condo. It costs less per night than a hotel, and if you have more than 2 people is way more comfortable. You can save some meal money by cooking meals in. Every place that we've rented has had BBQ grills so we grill out at least twice during the week. If you want to use the pools, check to see if they are heated, only about half the places have heated pools and they are a must in March.
If you insist that every game you see has to be a Rockies game then watch them on the road as well as Salt River. Get around and experience the other stadiums, each of them are nice in their own way.
Unless you are a Cubs fan, AVOID THE CUBS! They draw sellout crowds to all of their games home and away. This means traffic, difficulty parking, long lines at concessions, etc. The Giants are almost as bad, and forget getting tickets to the Giants unless you go on the secondary market.
There are places that you can walk up and get good tickets. Goodyear for either Reds or Indians games. This may change a little with the Indians winning the AL, but they mostly have a regional following and don't fill up the stadium. Camelback Ranch when the White Sox are home is another good bet. Surprise Stadium for Rangers home games is usually an easy ticket, and often for the Royals, especially on weekdays. Maryvale Stadium (Brewers) usually has good tickets available. Again, with all of these avoid the Cubs and the Giants.
The stadiums are generally much busier on Fri-Sun than on weekdays. If you decide early which games you want to see order tickets ahead of time!
If you are taking kids and want something to do other than baseball Phoenix has a great zoo, it is bigger than Denver's. The Arizona Science Center also won't disappoint azscience.org. Hiking trails can be found many places in preserves within the city limits, get the feel of the desert and climb some of the hills for some great views!
Hope you have a great time and Go Rockies!