Harvey,
I have a 37g too, 24"l x 24"h x 18"w. Have a pair of ocellaris in it. Am thinking of other fish to add to this tank as well. If anything, may consider a 6 line wrasse (which you already have) or a royal gramma. The problem with a 37g is that few active fish will fit into such a small tank, plus I don't want to overstock.
As for the longnose hawkfish, they grow to 5" and can be aggressive toward other fish:
http://www.marinedepotlive.com/543594.html
We had a spotted hawk in our 42g hex. It grew to max size (3") in no time. While it was an interesting fish, it went back to the lfs because it was too aggressive for such a small tank. Man, it would stare us down from its perch on corals and rock
