I called Spectra yesterday to ask about printing 20x30" from my negs. They also told me that they no longer do manual prints from slides. They said they have to scan and print.
That said, try Fuji frontier prints at Colour Lab. Got some prints made from Velvia and Provia. I've never seen anything so good in my life, seriously. I never knew anyone could make such good prints. These were as good as the best cibachromes I've seen. However this was more than 1.5 yrs ago.