The OP asked for a place "near" to Ubon within a three hour "drive". Not "flight".
Besides, quickest Ubon to Phuket flight is in the region of 3.5 hours, return over 4. Add the drive time to the airport and the waiting time, etc. 5+ hours.
It's obvious you are attempting to continue putting Isaan down in almost all respects. However, your disdain does not do the OP any favours.
To the OP, I would be inclined to travel along the Mehkong heading north. There are some lovely spots. You will unlikely find all the activities you are looking for but you will certainly find a nice "retreat".