Wow, thanks for all the help everybody.  So much information to consider.

As much as I like the practical consideration in interlingua that learning it is apparently a good stepping stone to understanding romance languages, that isn't really my main goal, so the extra complexity there would probably exasperate me.  So I think I'll look at Ido for now and see how it goes for me.

I did skim the past month or so of posts just to get an idea what people talk about here, and one of the threads caught my attention.  I'm paraphrasing and hopefully not misrepresenting too much, but I think it was about some languages like interlingua being constantly pulled toward more and more irregular grammar rules because native speakers of romance languages keep trying to turn it into a clone of their native language.  I have to think, that's what you get for using too many words from real languages in the vocabulary.. the native speakers of those languages feel entitled to re-shape the rest of the language in their own image too.

I want a language that's at least somewhat immune to a constant pull toward irrationalization like that.

 - Mark