The company I work for wants us to basically keep hotels under $70 per night pre-tax, although I travel mostly to Atlanta for meetings, and stay at the Hampton by the airport which is more than that--but it's difficult to find a decent, safe hotel in Atlanta where I won't need a rental car for less. I usually fly in the evening before, take the shuttle to the hotel. Then take the shuttle back to the airport in the morning and catch MARTA to Buckhead for $1 or so, and from the Buckhead MARTA station the building that my meeting is in is a few blocks walk.
The other option would be a cheaper hotel and a rental car (I won't take MARTA at night--I usually do'nt get to the airport until well after 9:00pm) which would cost a lot more in the long run. Breakfast is free at the hotel, dinner is usually a slice of pizza or Chinese at the airport, so no expensive meals for me.
Years ago I had the best job as far as per diem's went. I worked on the road crew of a bunch of bands. You would jockey for the best tours to be on--which weren't always the biggest bands. On show days you got hot breakfast, lunch, and dinner, plus a snack after the show (bus food) and on a "good tour" you did "three on, one off" so worked on average five days a week. All transportation and hotels were covered, unless you wanted to take a cab or rent a car on your day off. We got $210 cash--not reported as income--per diem per week that had to cover meals on dark days and any personal expenses--it was pretty easy to end up with well over $150 of your PD money tax free in your pocket at the end of each week.
Add in the perks like free entry into concerts and clubs (with free drinks) on your nights off, free CD's from label people, free clothes fron sponsers and the tour merchandise, free laundry service, the bus was always stocked with soda, milk, coffee, tea, snacks, cereal, fruit, beer, wine, and liquor, etc. by the promoters, it wasn't a bad deal.

Not to mention that because I was usually the only female on the tour, they always gave me all the flowers that the chicks gave to the guys in the bands...
Anne