I'm an Emerald Club member and used The Aisle. When I arrived, since I had already made my reservation, I bypassed the desk, walked to aisle, and picked from several mid-sized and full-sized sedans. Cleveland is the city that raised me, and National Car made coming home pleasant. Getting the vehicle was a breeze. Then on the return, I dropped the car off after hours for an early flight back to ATL and I happened to catch the Shuttle Bus. Actually, he saw me pull into the lot, and waited for me (The bus was just about full!). So nice! This experience set the bar for my Emerald Club membership.
I try to use only National for a number of reasons: First, they are usually the cheapest in their daily rates and their is very little difference in rates between car categories, so I can get a smaller car if it is just me, or a larger car if traveling with a team and not have to worry about a large increase in cost. Two, the Emerald Aisle advantage is huge, just walk up, pick your car, show your ID at the gate and drive off. Best rental company out there, hands down.