Colorado is the easiest generally speaking to get otc tags or to have a more liberal tag limit in most units. I have been guided in Colorado 2 times for elk and will be going for a third time in 2019. You need to decide what shape you and your dad can realistically be in before really settling on a certain area. I used mountain view adventures in nw Colorado but the area is rough country. I was successful my first time but not my second. The 1st and 4th seasons are draws but we have never had to have preference points. There are multiple trophy areas surrounding 21 and 30 and there are some monsterous elk in the area. I killed a 300 inch bull and they had a few people kill bulls in the 380s. The average would usually be a 230-250 I would guess. Unit 21 is a trophy mule deer area so if you want a multi species hunt then your only option would be to wait 5 or so years and hope to draw a tag in unit 30. 21 will be a 15 plus year wait. Other areas are much more liberal if you want a multi species hunt. Good luck with whatever you decide.