I can read well enough to get impressions, but not to actually comprehend. Reading is my strongest point; my listening was always pretty poor - speaking and writing are basically gone now.

Of all the options, French and Spanish would be the easiest, but they would still be a lot of work. The immediate problem with French is that I don't have any useful way to maintain it, whereas Spanish is indispensable given my geographic and demographic proximity to Mexico. In that respect, French is actually the most difficult; Maria is a native Russian speaker, Walter speaks Mandarin almost fluently, and my lil' sis even knows some Japanese.