i dont bother with transfer to sousse its max 20 dinar in taxi if you dont mind to haggle and make sure price includes luggage and is not per person 15ish return
there plenty places to exchange money when you arrive in airport (check it befor you leave counter and keep receipt)
take all sun lotion and toilet stuff with you in can be expensive there
couple half bottles (or full) of good whiskey can be great idea for gettting perks (hotel manager for kepping room on day you check out or instead of tips)
travel kettle for room if you like a brew as very rare to have them in room (powder milk) or fill a pocket in aiport as you leave as i do and sugar sachets
top tip for me is i always print 10+ mini money exchange rate tables befor i go and laminate them to keep in pockets bags etc for shopping trips.
also i take couple 2way walkie talkies complex can be massive and there great if your in one shop and mrs in another looking at same thing and trying to get best price local shop keepers soon drop the price to get the sale
if you smoke Mars red are ok and a good price