Well you'd be nuts to do an even swap because the thunder is worth a ton more than that sign is if you want to go small that's fine but they'd be a lot of money going in your pocket if you're switching that vehicle for the other and you want to make sure that that Scion doesn't burn oil cuz many of the 2.4 is in those do

I was looking for a 2006 tundra and eventually gave up because their prices were skyhigh even private party. Do not trade it in; sell it yourself; you will guranteed get buyers that will offer top dollar for that thunder. The xb's burn oil so just get a camry v6 or something if you want fun. 

How about buying another cheap reliable daily like a Fit or Yaris? Keep the Tundra as your weekend toy?

Sure, you would want to sell the Tundra and buy the XB for a lot less, it isn't worth much. The 2008 XB is known for oil burning so you would want to beware of that.

Nah, I would keep driving it or get something else alongside. The XB was not great and was known for burning oil with those 2.4 L engines. Maybe look at a Venza or RAV-4.

Not a great idea, as you would lose a lot on a straight up trade.

Only if you end up with a load of cash in the end. even up trade is just plain daft, not a good idea. Tundra worth a lot more than xB