We've got some visitors in town and we're trying to work out which would be the best experience. Would like to do both but bit short on time! Also if there's any of these tours to avoid, please do advise. Ta.
I've done both. The dinner cruises are a waste of money.
The Creek is undoubtedly interesting and does make you feel as if you're in the Middle East - but a provincial Middle Eastern city circa 1985. The interesting stretches alongside Bur Dubai and the gold souk area of Deira are small and you go past them quickly. The 1 AED abra hop across the creek pretty much shows you what's to be seen.
On the other hand, the Marina cruise is about Dubai as the world currently sees it. Lots and lots of tall shiny towers. It's more impressive in its own way.
If you want to show your guests a side of Dubai different from the malls and Burj Khalifa, do a walk through Bur Dubai from the museum to the creek, take an abra across, explore the gold souk and wind your way through the covered souks (sadly becoming infested with shops selling cheap tourist tat in recent years), have a Pakistani or Persian grill and head to a Deira hotel nightclub near Baniyas Square to dance the night away with the Russian mafia.
If it's about having the tour not the food you can still rent a small boat (old or new) from the creek side for AED 120 per hour. You can bargain and get less price. It's smaller and have better view, and you can still take it in day or night.