Louisiana has more or less been phasing out its interstate rest areas with the exception of the state welcome centers and a few scattered survivors.
These have been closed, virtually all in the last 15 years:
I-10: WB between Sulphur and Vinton; some concrete remains, but is located far back from the highway
I-10: a pair east of the Mermentau River crossing east of Jennings; virtually nothing remains
I-10: a pair in Lafayette; EB was located just west of the Louisiana Avenue interchange, WB was located just east of same interchange; little if any remains exist
I-10: a pair between LA 3000 and LA 77 west of Grosse Tete; few remains
I-10: a pair between LA 22 and LA 44 in Sorrento, just west of the LA 941 overpass; few remains
I-12: a pair just west of LA 441 in Holden; looks like they were very bare bones; you would never know they were there from the highway, but some remains exist behind the trees
I-12: a pair just south of Covington just west of the Tchefuncte River crossing, now an exit for a recently constructed local road leading to two large shopping centers
I-20: a pair east of the LA 159 exit in Haughton; substantial remains exist per Google maps
I-20: a pair west of the LA 154 exit in Gibsland; some remains exist; these were apparently not very elaborate in any case and were probably similar to the still-surviving Choudrant rest areas
I-20: a pair between LA 17 and LA 609 west of Delhi; some remains exist; bare bones like their cousins to the west
I-20: EB opposite from the welcome center near Mound; identical in design to its cousin; ROW is still demarcated but no remains otherwise
I-55: NB just north of LA 10 exit; concrete remains but hidden behind trees
I-55: a pair north of the LA 3234 exit and south of the LA 1064 overpass in Hammond; these were nice sized facilities; the SB has substantial remains, while most of the site of the NB rest area is covered by an apartment complex
I don't think there are any closed rest stops on I-49, which was constructed with minimal facilities (there is one still-extant rest stop/day-use area in St. Landry Parish that serves both directions).
DOTD probably considers the rest areas' original reason for being to be obsolete, given that nearly every highway interchange now has at least a few traveler services (and a Waffle House

) - not the case, of course, when the interstates were new and the interchanges unspoiled by development.
It was claimed here:
http://online.wsj.com/news/articles/SB124656938899088487 that the state closed 24 of 34 rest areas between 2000-2009, so I think that captures all but one of them.