Good vehicles?

I'm not a regular in this forum, but looking at maybe trading my wife's 04 trailblazer on an 05 sienna le 7 passenger 3.3 v6. Is this a good vehicle? What kind of mileage can I expect? Her tb has the 5.3 v8 in it and mileage has consistently gotten worse and worse, was 18 or 19, now she is getting like 14, runs fine and all, don't know whats up with it, so time for it to go. Is the sienna in that vintage a good vehicle? It has 69k on it.

Consumer Reports got 12 mpg city and 30 mpg highway for a 2004 Sienna with 3.3 engine. The 3.3 has timing belt, due for a change at 90k miles. Body hardware seems to be the only major problem. 2005 was the second year for this body style.

I would put it as one of the best minivans out there.
You should get a better, more comfortable ride, better fuel economy and LOTS more room inside as compared to what she is now driving.
The Sienna is the most "car like" in ride and handling of the minivans.
It is also a very reliable vehicle as compared to most of the other minivans out there.
Timing belt is a bit complicated to replace.....I chose to have mine done at a shop.......but a timing belt makes the motor quieter then with a timing chain.......
The newer model with the timing chain......they increased the sound proofing to quiet the extra noise.
But, at every 90K.......it lasts a while.
The motor is peppy and economical.
As with ANY vehicle you plan to hang onto.......read up on the web and learn the potential problem spots.....and then keep and eye out for them......and include things in your routine maintenance to prevent them from happening in the first place.