Piggybacking off of the on point cash bar thread, I give to you the guide of what your actions of bad etiquette say to your guests. They may not say it to your face or ever bring it up with you, but I guarantee you your relationship with them will change to some extent. I don't think it's any coincidence that the people who treated their guests like crap at their wedding are usually the ones that complain they don't have any friends a few years down the road.
Remember perception is reality. I have said it before and I will say it again - you ALWAYS have the option to do the right thing. It may take some tough decisions and sacrifice but will always serve you and your guests best in the long run.
Invitation to shower but not the wedding - "you are not good enough for me to host you on my special day, but I really want to celebrate my marriage with you so I will have someone else host you on their dime. But since this is a gift giving event I do expect a gift. In fact, go ahead and spring for a REALLY nice one considering this is the only wedding related event you are invited to."
Invitation to ceremony but not reception - "you are good enough to watch me get married but not good enough to host you at the reception so I will give you the "honor" of coming to the ceremony since it costs pretty much nothing for me to host you there. But I am expecting a gift so remember to bring it with you to the ceremony."
Invitation to the reception but not ceremony - "you are not good enough to watch me get married but I guess you are good enough to come to the reception. Don't forget your gift and it better be nice because I am actually spending money to host you there."
Invitation to a tiered reception - "you are not good enough to watch me get married OR for me to host you at the reception, but good enough to come towards the end so I don't actually have to include you in the head count. If you are lucky you can get a piece of stale cake. But don't forget your gift because technically you were invited to at least part of the wedding."
Gap between ceremony and reception - "our ceremony site had to be booked early but we want all the trimmings of an evening reception so find something to do for a few hours. Sorry we didn't have the foresight to think that some of our guests would need to pay for a few extra hours for a babysitter, go home and let their pets out, or just find some way to kill time in dressy clothes in the middle of the afternoon. But it's our day and we will do what we want."
Cash bar - "we either a) over invited, b) didn't budget correctly, c) don't want to make cuts in other areas or d) all of the above. But since we are such gracious hosts we will give our guests the option of drinking because dry weddings are so boring! And since we won't be footing the bill, no well drinks here. Top shelf for all! Hope you brought your wallets!"
Honeymoon registries, honeymoon jars, dollar dances, etc. - "give us money. Lots of it. On top of what you have already spent to get to the wedding and the gift. And we will soften the blow by asking for it in a "cutesy" poem."
I'm sure there are more just thought I would throw a few out for entertainment. I really like this board, never used The Knot when I got married 7 years ago but was ran off from The Bump by some crazies. Hope you will let me stay.