Thanks Howard for your review, I learned a bit more about the cars. I was already leaning towards the Lotus (although you can buy two MX5 for the price of an Elise, at least in Portugal), now I am even more.
My wife isn't exactly a petrolhead, but she did do Lisbon-Inverness-Lisbon with me in a motorbike; Lisbon-Shelsley Walsh-Lisbon in a Plus4; and lastly Malvern-Dublin-Kilkenny-Bristol-Portsmouth-Santander-Lisbon in a M3W, so I don't think the Lotus is a problem for her, both driving or as a passenger.