So weddings are about being true to ourselves as a couple. Something I have noticed at the few weddings I have been to is the amount of waste involved. I mean garbage bag after garbage bag of stuff thrown out. I really don't like to be wasteful. I at least try to recycle, but really its about reduction. Minimize the amount of stuff used, only what you really need.
I've seen negative arguments for renting plates/glasses/silverware (i.e. impersonal, feeds the wedding industry, etc). But really, it's an incredibly sustainable thing for the WIC to be doing. Rental companies purchase high quality, timeless items and then allow brides to reuse them. Some argue it is more cost efficient to purchase at thrift stores. I have nothing against mismatching plates, I just don't have the time or energy to seek out 200 dinner plates, or store them. And then they'll just be donated again, because you can't sell them back to a thrift store (I suppose you could try etsy/ebay). It's too much work for me, I'll just rent, and know that I will have enough of everything on time and then give them back.
I understand they make very fancy paper/plastic/bamboo plates and utensils nowadays. But even when using compostable materials, you must ensure that they are actually being composted. Putting biodegradable materials into the trash which is sent to a landfill will not allow them to biodegrade. They will be in bags, out of sunlight and away from nutrient rich dirt needed to break down the materials.
This is essentially my argument against wedding favors. I have yet to see anything truly eye catching that people won't just throw away. I suppose food is a good one, but most of those special treats are in fancy packaging that still gets thrown out. That plantable cardstock is pretty cool, and they make some that doesn't look like the paper I made in 3rd grade with a window screen. But how many people do I know that have gardens and/or will actually plant it? It's also why I'm trying to minimize decorations. With flowers, I know that when they die, we will be able to throw them in the backyard to degrade properly (because the reception is at my in-laws' home).