Lane, you fall into a very large group: folks who hope to go cruising and who are trying to pick the right boat for them, but who haven't yet faced (or at least shared with us) your specific cruising plans. If like most North Americans you plan to visit the Caribbean
for a few years (and then, again like most NA sailors, sell the boat and buy an RV or get into some other endeavor), either choice will suit you well.
If however you hope to do some long-term, long distance cruising - or at least you'd like to leave that option open for future consideration, neither of the boats you mention would be my recommendation. The 35' cat is too small for some of the jobs that need to be done (e.g. it can easily do the Milk Run down to NZ and Oz...but what about getting back? it can sail TO Hawaii
but would not be suitable for returning) and the 51' mono is probably too big for your use.
Firm up your plans and then repost your query.