Forever stamps are first class postage forever. Thus the name. Put them on your RETURN envelopes--the SASEs. Don't waste them on your outgoing mail. You're mailing it today, postage rates aren't changing between now and Friday. I swear.
No one cares how many stamps you have on an envelope.
From an aesthetic standpoint I like one stamp, but yanno..it's not something I give a rat's ass about. I do notice cute stamps and new stamps but only in a very very cursory way and cause I look at a LOT of stamps in the course of a week. I don't remember you sent something with a particular stamp. I just notice cause I'm sitting here opening mail.
Every time you start obsessing about stamps I want you to stop, think, and return to your desk. For every wayward stamp obsession you owe me twenty minutes of writing.