I may be headed back to WY this September for antelope also. I've done two antelopehunts, both DIY. The first one I had only a doe/fawn tag and killed a doe coming to alfalfa. The second one I had an either sex tag and hunted 45 miles west of Casper. Lots of antelope but they weren't using the waterholes during the hours we were watching. One of the three in our party killed a buck antelope. I didn't get any closesr than 80-100 yards. We were too late for decoy use.
There is lots of public land with thousands of antelope thanks to the Walk-in-Hunting program. WY has good maps of these lands too. However, if you can afford a guided hunt for sure that would be the way to go. I turned down an alfalfa hunt on a ranch I used to hunt every year in the 80's because the access fee was $500. The fee exists because the rancher has leased the place to some out-of-state hunters and they wanted the $500 (each) to allow my buddy and I to hunt their lease with bows.
This was probably very dumb because this ranch has irrigated alfalfa and the fields have antelope in them all day. I just thought $500 was too much money -- I know, I'm using faulty math: Gas cost $600 there and back, license is $286, we could camp for free on the ranch, etc. DUMB of me to turn this down as I'm 99% confident we would have killed buck antelope.