I am planning to travel within Spain between May 27 and June 8. My planned overnight stays: Madrid, Toledo, Granada, Seville. I will be happy if I stayed at some Pensions. Being that I am on the brink of tourist season, is there a necessity for making reservations at any of those cities' pensions?

I am sure you can find a place at any of those cities once your there. I guess it depends on how you like to travel, if you like walking around w/ your luggage i presume, sometimes lost trying to find addresses of hotels, you can probably swing it. I would sugges at least making first night reservations, then calling place a night or two in advance. I find it easier to have my arrangements made b4 I depart, loosley as your travel plans can change, so place require a deposit, which is sometime refundable or not if you decide to cancel.

maestroyaron,

I too don't believe you will have any problems finding lodging. Just a couple of suggestions from someone, who like yourself, did not have reservations when I arrived in a city.
If you are travelling with your significant other, she can wait in the train station and guard your luggage as you try to find lodging. And try walking around the train station. There are sometime kiosk with people there to offer quite a few lodging options. I know there is in Sevilla, and there used to be in Barcelona.
Last time in Barcelona, I couldn't find the kiosk but, as I waited in the train station, with our luggage, an agent for a hostal came up to us and asked if we needed lodging. That is where I ended up. So, with a little patience, reservations aren't a necessity, but they are handy.