I've sent some of mine to a local print house too and was very satisfied with the results. I did them in several sizes (from 20cm width the smallest to 50cm - 20 inches? - the widest), all printed in glossy then framed (they went to an exhibition later). All had 300dpi and were huge - some had 100Mb. It wasn't as expensive as I thought (the framing is much more expensive), and the only problem I had was that the ink used wasn't water resistant (HP ink?) - some got destroyed by small saliva droplets, I should have stopped drooling when I saw these images... I never tried zazzle neither ophoto and similars also because of the shipping costs - I couldn't pay this (international) shipping then another shipping to send them to the exhibition place.