Vacuum and Owner

I run as user "spry" on psql, I created the database as "spry" but when I
run vacuum, all the system tables get skipped because "spry" is not the
owner. Is there a way to fully vacuum my db and the system tables as a user
other than "postgres"?

Is is very important that the system tables are "vaccumed" in addition to my
db tables?

Matt Friedman