I did something similar with my now-11 year old. She was a horrible sleeper as an infant (we moved to Germany and back in a matter of 4 months, and it REALLY screwed up her little time clock!), and she didn't start sleeping through the night on a regular basis until she was 2 1/2. Ugh.
I had a full time job, and so did my husband, so when she would wake up in the middle of the night, one of us would go in to her room, lay her back down, and pat her back. Then we would curl up on her floor next to her until she went back to sleep. Sometimes, we ended up finishing the night there (like you said - we were exhausted!), but most of the time we would be able to sneak out about 20 minutes later. Once she realized that we weren't going to do anything but lie there, and not interact with her, the pattern stopped.
That lasted about three months, and after that she was a normal todddler...
I'm sure it's a phase with your daughter, but do what you need to do to keep her in a routine, and what you feel is best for your lifestyle!!!
Good luck!