The open house sounds perfect, but I love entertaining this way. Make the hours fairly long so the numbers won't overwhelm you, and you can even give different people different start times to avoid crowding. People come, eat, coo and go, so they won't all be there at once. Unless they are all having a truly superb time, and then they will manage nicely.
I wouldn't try to do it alone, though, or just me and the spouse. I'd have the house cleaned, order the food (unless one of us really, really wanted to make giant pots of chili or something, or a sib/friend wanted to show off her/his fabulous lasagna, but ordering from, say, your local Indian restaurant won't set you back much more than groceries would) and hire some college kids (high school kids, depending on which are more available locally) to do table replenishing, periodic and final clean up. Invite everyone! It'll be fun. Do it when your husband's family will be in town. I like after the wedding. Before, too much excitement will be focussed on that. You want quiet, with everything centered on Bundle.
"Having the house cleaned" can mean by DH or close friends/relatives who ask to help. That, too, can be a fun "preview." "Ordering the food" doesn't mean it needs to be more than cookies and coffee/tea and a cake or two from the bakery (you have to replenish every hour or so with new stuff) or see above. The clean-up kids (who could also do the first clean and set up) will be happy with minimum wage or a flat fee. It does not have to cost much to have a quite correct good time.
