The best replacement for guest is tenant.

The best alternatives to guest are rated as following:
★★★★★  tenant
★★★★  customer
★★★  guests
★★  visitor
★★  guess
★★  host
★  occupant
★  invitee
★  degas
★  pest
★  standard user
★  user account
★  noob
  slenderman
  limited account
  guest
  houseguest
  power off

Your alternative for guest is not listed? Suggest!
Speaking about guest, one probably shouldn't forget about priority pass.

Other search terms related to guest and their ratings are:
★★★★★ priority pass
You have in mind a companion for guest and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of guest in all years. Click on graph for more.
guest
tenant
customer