Along with coolers, how do you pack the meat in there to age? Meat right on the ice or in the gamebags or in plastic?
I've not noticed a difference between having the meat in game bags or not in game bags while in the cooler. Any meat touching ice/water will get a little discolored whether in the bags or not. A barrier of plastic or tin foil can help with that, but make sure everything is cold before you add vapor barriers like that.
Having the meat out of the bags (just laying the quarters right in the cooler) makes it easier to arrange for good air circulation and efficient use of space. If you just plop the game bags in there, your backstraps are all balled up, bones poke into soft muscles, etc. Also, the flatter/thinner you can get your meat in the cooler, the faster it will chill to cooler temps. A big ball of meat takes a lot longer to get cold in the middle.
As for your original question. I just got back from Wyoming. Two hunters, filled three tags. We had a few coolers and lots of extra ice. You can fit a quartered (4 quarters plus backstraps and trim) antelope, plus ice, not counting the head, in a Lifetime 55qt easy, a little tight in a Yeti 50 (which is really only like 45qts). Three quartered antelope plus 5 frozen 1 gal jugs will fit in a Yeti 125.
If it's warm out, you'll need extra ice to cool the meat down fast. Plan to burn half your ice just doing that, in a separate cooler if possible. (If you shoot one in the evening and it'll be cool enough overnight (mid-40s or colder), or if it's cold enough during the day, hang it (or set it on the roof of the truck) until it's at ambient temp to save on ice.)
Having 3 coolers was nice for this as one held extra ice, one we used to chill the meat (frozen water bottles were nice for this as they can fit in irregular spots and can be used as camp water once melted), then moved the cold meat to the big third cooler for storage, that just had a layer of gallon jugs in the bottom, and all the cold meat on top. For the drive home, we had enough cooler space left over from the used-up ice that I was able to put the head of my buck in a cooler too.
One other note. We brought out two coolers filled with frozen 1 gallon water jugs, and the other filled with frozen 16oz water bottles. While the gallon jugs definitely hold ice the best (still frozen, over a week later now), they limit your packing/arranging/space utilization options within your cooler a lot. They take up so much space you just don't have very much flexibility, and can't fully capitalize on your cooler space. I think a sweet spot is probably half-gallon jugs.