Cheers for all the replies. Ive booked Elfin from here http://www.ozhouseboats.com.au/houseboats/open/main.htm
Talked myself into a 6 day trip, and spalshed out the extra for the spa, 'just in case'.
My only issue now is how to get to Murray bridge from the CBD.
Not sure its worth hiring a car to do a 90 min drive and leave it parked for 6 days, but it looks like theres only 1 bus a day that goes there? 9am there and 4pm back to the city, both via mt barker?