You need gain for the popular Butterworth a.k.a. maximally-flat frequency response, Q = 0.707. In that case the gain is about 1.585. If you extract the signal from the inverting input of the opamp you will have unity gain in the passband but a ~high output impedance unless your gain-setting divider network is very low-Z (which may be hard for the opamp to drive). If you buffer the input(s) with a follower you can get the low Z but at the cost of another opamp.
See this for examples of SK filters with equal R equal C:
http://www.engr.uky.edu/~gedney/courses/ee221/project/Active_Filter_Summary.pdf
That ref. points out that Q = 0.5 is the lower limit for equal R equal C, which does correspond to unity gain in the passband.
With equal R and unequal C's you can do Sallen-Key unity gain lowpass; with equal C's and unequal R's, Sallen-Key unity-gain highpass. There are other topologies with more opamps but Sallen-Key is cheap and easy.