[Dfrank330]

I am looking to purchase a used tiara 32-36' and seeing both diesel and gas models. Diesel fuel at the dock in Florida is cheaper in Florida. What are the plus and negatives when deciding between gas or diesel. Thanks

[Sapphire]

Conventional wisdom will suggest diesel is preferred in larger vessels due to the torque these engines develop to move the heavier vessel. That's why most boats 36 foot or more are diesel. Many will argue diesel is safer as it does not readily explode should a leak develop.  Diesel tends to have more maintenance cost.  
I think that in this size vessel gas is fine, although you will find arguments on both sides.  Google it, you'll find lots of opinions.

[MC1600]

Ditto what Sapphire said. Whatever you do, don’t just base it off the price per gallon because that changes frequently, inconsistently, and can have variable impact based on usage.

I just sold two gas engines for two slightly larger diesels. Diesel parts are more expensive, but I buy fewer of them. Fuel burn is almost identical between my older gas engines and newer diesels (in a bigger boat). I did most of my own work on my gas engines but need a little help with the diesels. Diesel is “safer,” but once it gets on something it’s almost impossible to remove the diesel smell.

So it’s all about treadeoffs and your preference.