Mid-size suv would be tight with two in the backseat depending on the length of your skis, and this might not fit lengthwise unless you put them diagonally. Doable though but you'd be packed to the brim with luggage too. It might be more worthwhile to spend an extra $100-200 (cost of rentals for 3 days for 1-2ppl) and get a full size suv, and bring your own skis. For a family of 4, even $300 extra for the big suv could be cheaper than renting skis, depending how long you stay.
Depends who you are flying with too. Southwest? Absolutely? Anyone else....consider baggage fees each way and that could add up with a family of four. Bring boots on the plane as a personal item. I'm sure you know this, but never check your boots.
From experience a few times, Christy's is the way to go but rent the demos for yourself, nothing less. They're less than $30 if you pre-order and pick up in Denver. If you get in a mountain town, add another $10-15. I've rented in both Lakewood, CO and SLC for various reasons of not having my own skis and got Candide 3.0 each time. Condition of skis were decent.