Well, Hope it is not too late.
Just back from a driving trip to barcelona 2 weeks ago.
So for spain can only comment on barcelona itself.
Weather there now is very sunny and warm, and the flowers are blooming along the highway.
Things to shoot are mostly modern design buildings and street photography(if u are into street photography). Buildings by gaudi is a must for you to shoot, not to mention park guell and sagrada family temple.
If i were to go there again, i would bring my film slr fitted with reala and if possible some b&w film (for street photography). A monopod is more useful than a tripod for me, i think in barcelona.
And, you need wide angle lens for all the amazing buildings, so 17-40L fits in, and the tamrom lens on film camera for all ard shooting plus detailed shooting on inside the buildings. Think should be enough. 50mm lens is not that crucial i think, except that during my stay in barcelona i used it (X1.6 on 300D) to shoot detailed structures inside the buildings low light condition.
Barcelona is very safe, comparable to munchen in germany. Don't worry about security, as usual, pickpocket is a common scene in europe, but there it is not as notorious as those pickpockets in rome metro.
And another thing special is that barcelona ppl flock onto the streets after 9PM and stay on partying till ard 1-2am. It is like they are sleeping in the day and coming out at night enjoying, unlike most cities in europe whereby after 9PM there aint much activiy.
So please do enjoy the night life of barcelona.
And for buildings in barcelona, i am amazed at their city planning, the buildings and residence are nicely arranged and formed squarish block of building groups. You can check out on the map and know what i mean.
A nice place to take overall city photo is at the hill beside the olympic park, you can have the view of the special squarish block and including the segrada familly temple, plus the special formation of the diagonal avenue.
P.S A side note, in all cases, DO NOT ALLOW a female getting near the ZARA headquarter in Barcelona, it is a huge building and loaded with all the new designs and some special zara designs which you would not get in France and Italy and elsewhere. Plus the stuffs there are dirt cheap, abundance of zara shirts at ard 5 EURO and is the cheapest in europe ZARA shop.
=> means that it is a potential time killer, my gf spent 3 hrs there, not to mention the other girls that went along with us.
If in any case you are stuck with ZARA, a good suggestion is to tell the girls to continue shopping inside the ZARA HQ and for the guys, can take metro to the football stadium. Me and some of my frens chanced upon ronaldinho inside the soccer coach heading into the stadium while we were there, and everyone are screaming at the highest tone. ;p
Well, hope that it is helpful.
Do enjoy ur spain trip.
Cheers