Data sims in Europe (Spain, France and perhaps Italy)

We travel to our place in France 2-3 times a year, my parents holiday home in Spain 1-2 times per year and plan to visit our friends in Italy, and I would like to be able to continue working whilst doing so. I have this time rented a mifi with unlimited data whilst in Spain and want to buy my own and sort out a data sim. What are the best options available to me (I need to access emails, work online (WordPress and Adobe) and occasionally download programmes to watch offline, or maybe stream, via BBC iPlayer)? Am I best to look at 30 day sims for each country as and when or do you have an option of an ongoing contract for Europe? The 1GB data sims would be too low I think. Thanks.