You're going to run into massive endogeneity issues on anything related to micro-level inequality, but the GWG is done to death until somebody figures out a nice way to figure out what's going on with gendered selection into career paths. I imagine a UG thesis advisor isn't expecting something groundbreaking, but if it was me I'd rather at least try to do something original.

One area that might be worth looking into is intergenerational mobility, as this has important implications for inequality and opportunity. There's been a lot of work on this, but frankly, a lot of it hasn't done much to improve on what we knew in the mid 1990's, so even if you don't end up with something publishable, you'll probably be able to at least satisfy your own curiosity about some undercovered aspect. One potentially easy way to start would be trying to explain the Chetty et al. county and commuting zone mobility levels as a function of some spatial/place-based process, and then maybe moving that into a micro analysis using NLSY/PSID data.