I love my cabelas "tin" chaps, they have zippers but are lighter weight than the filson double which is what you have to step up to to get zippers.
I also have Under armour which are really comfortable and great for walking in fields or thinner stuff. For really tough cover they aren't the best in my opinion.
I also wear the cabelas guide pants which I got on sale. They have suspenders which I like more than I thought I would but they are a little insulated and can get really hot early in the year.
Ultimately I think chaps offer the most flexibility during the day and can be thrown over anything to help cut the wind, rain, or coldfront moving in.