Hi
We have this dilemma as well as we are only out for about 6/7 times a year and although we would like the plants in the garden to grow I don't want the weeds to grow with the same vigour!  We have used most of the plants that we inherited i.e. the cacti, arum lilies and a fantastic trailing plant, which looks like a tradescantia (wandering jew), which produces very tiny dark pink flowers and isn't too bothered with lack of water.  We tend to just see what plants are growing wild near us and try to copy that.  Without being in Spain full time it is very hard to garden proficiently.  I do bring out my geraniums from my English garden when they have finished here and just plant them out; if they survive it’s a bonus and if they don't nothing lost!
It would be great to hear everybody elses tips
Debbie