Stayed two nights at Hilton Garden Inn Downtown early August last year. First time actually stayed in Dallas - transited many times.
Apart from being an extremely cough time of year to be there (temps 40+), the hotel was functional. Very close to a DART stop. Basic buffet breakfast. The restaurant hadn't opened (newish hotel), but should be up and running now.
A little further from tourist bits (but not much more). Also cheaper than other options. But more than a couple of nights, the the Homewood Suites might be nicer? Mind you, 1 day was sufficient to tick the tourist attractions IMHO!
For $2.50 (and ~50mins) each way on the DART, a DFW / Downtown Dallas o/n stopover can be easily done.