I eat out a lot, and I love watching and flirting with good-looking waitresses when I am out on the road for work. Not including any of the breastaurant chains, which chains seem to consistently have hot waitresses?
In my experience, Buffalo Wild Wings has been a reliable spot. In the last town I worked in, there were so many hot college girls in leggings and yoga pants working at BWW that I ate there every night. Second place would be Texas Roadhouse. Looks aside, if we are talking about which waitresses are the easiest to lure back to your hotel, that would be Waffle House or IHOP in my experience.
In my experience , the restaurants that are the busiest have the best looking waitresses. Most restaurant managers "want" to hire cute girls. It's good for business. But the hot girls have choices and they will either go to a place that is "cool" or where they can make good money. The new hot spot in that city is the logical choice if you want to see cute girls. Also, eating close to a major university does increase your chances also.