Hey Kenneth!
When purchasing tomato seeds or starts you should look for varieties that are about 60 days or less to maturity. I’m sure you’re growing season is quite short at 7,500 feet. Row cover, Hotkaps and Wall-O-Waters can help start your season early and extend it into the fall.
Choose an indeterminate variety if you have ample space to trellis and would prefer a vining plant. Choose a determinate variety if you have minimal space or are using containers. Determinate varieties have a bushing growth habit and will be shorter and more compact.
Some varieties we carry in our store that would fit your needs include:
Large Fruit: Ararat Flame, Stupice, Moskvich, Cosmonaut Volkov, Early Girl Hybrid
Small Fruit: Sungold Cherry, Pink Princess Cherry, Black Cherry
Hope this helps!