If the date of June is a given--and I think it is, and I don't blame you, I would head from Oklahoma to Colorado.
Of course, I have no idea about your previous experience. Perhaps you have already been all over Colorado and are ready to visit Utah. I love them both, for different reasons. I'm only responding to the fact that Colorado will be more comfortable in June and July.
No need for me to comment on all the wonderful possibilities for places to visit in Colorado. If you should decide to go that way you will get really good suggestions on this forum.
For that matter the same can be said about parks in Utah.
