We kept all of our hong bao and they actually did cover the cost of the wedding entirely, with some left over. My husband was in his 30s by the time we married though, his mother had passed away 2 years before, and his father was in his 80s and was not interested in our hong bao in the slightest. My husbands brothers and their wives helped us out quite a bit with the wedding and what we did was give them all of the leftover rice, liquor, cooking oil and other (uncooked) food. While this might sound kind of cheap, it actually was quite a lot of food that, for my husband's rural family, was quite useful (and they totally squabbled over who was getting what and it turned into a huge drama even though no actual money was changing hands!). All of the wedding expenses were paid for by us though so we certainly weren't going to hand over our hong bao to anyone else. I would say that whoever pays for the majority of the wedding is entitled to the hong bao money, unless they state otherwise.
There is the cycle of hong baos with our relatives/friends and us but it more goes like this, did we go to their wedding? Did we give them hong bao? Then we invite them so they have a chance to repay us. Likewise, if we invited unmarried people to our wedding that meant that when those people eventually got married we had to attend in order to reciprocate with the hong bao.
Like you said though, every family is different and the traditions are going to vary from region to region, village to village, family to family. There are some families out there who still expect a bride-price to be paid so obviously stuff like that would effect the hong bao situation a lot. What is your boyfriend's current view on the hongbao? Going without in order to make a statement is a nice idea but they can add up to a lot of money, and especially when you're just starting out as a couple that can be a nice little bonus.