Unusual tours around Madird/Barcelona

Browsing through the possible methods of sight seeing around Madrid and Barcelona, I came across quite a few interesting possibilities, mainly suggested on trip advisor. These were:

I am thinking for the weekend in Madrid, taking into consideration the limited time we have there and cost, we will probably go for the gocar tour. Plus they seem to have a deal on where if I blog about it and leave a review here, they will knock down the price as well. Sounds pretty sweet! I’ll write after wards and share some pictures to tell people how it went.