These guys were great.
I coordinated mostly with Chihiro and Javier was our tour guide.
I've been on a number of historical/walking/architecture tours in a number of cities. It's one of those things that I never thought I'd like (following someone holding an umbrella who is droning on about stuff you want to care about but you are not sure you care about)... but guides like Javier are what can change your mind.
When your guide has a passion for the subject and when your guide has some personality, it makes all the difference in the world. Javier has both. But you pay a premium to get the "Javier tour" and I'm guessing that it's worth it because he had the eight of us in this group (all friends who did a private tour) quite entertained. (Maybe ALL of their tour guides are great but Javier is who you pay a bit more for.)
His knowledge of the Sagrada Familia was encyclopedic but the trick for a tour guide is to not sound like an encyclopedia but, on the other hand, to keep the information and interesting facts coming. Javier kept things moving and entertaining so you didn't just feel like you were in a classroom. For what it's worth, he also knew his cell phone camera (and your cell phone camera) backwards and forwards and was giving some truly great tips on getting great shots at just the right place in the church.
Javier is a great tour guide and you will not be disappointed should you spend a few hours with him. (And Sagrada Familia is an absolutely beautiful church unlike anything you've ever seen before.) read more