OK...here's what I did, for those asking this same question...
I opened Pages, opened a New file showing templates, I chose an envelope template and filled in the Sender info with my name and address. I then went to File and hit Save As Template. Now, all I have to do is copy my addressee, open a New file, then choose my saved envelope template from My Templates. All I have to do now is replace the place holder with the copied addressee and I'm good to go.
Guess I was still thinking in Word rather than Mac. Tough to get used to. While I was at it, I also made up a letter template with my info already there. Again, all I have to do is put in the date, addressee and the body of the letter.