Probably nothing worse than renting the wrong skis, or skis you settle for.....a poor tune can be added to this. I bring two pairs on week long or longer trips, for shorter trips I'll bring one pair and take a chance. If however, you need to travel lighter, it pays to know what you like and what manufacturers you lean toward. I'm a Head skier, but like Blizzard as well, it must be my DNA. An Austrian thing. Call around before you travel and see what brands and models a shop carries. My wife rented once and settled, her week was horrid. She use to rent and buy if she liked something, most shops do this. If you were going to Vail I'd mention a few. I like the boot doctor in Breckenridge, but have also been railed in Breckenridge by one shop I won't flame.
Have a great trip!