Also, are there any PT students out there who also work full-time? If I wasn't working full-time this fall, I wouldn't even consider prepping over the summer. But since we have much less free time than full-time students, I'm wondering if there is some value in reading the E&E's in advance.
There's probably some value - but not much. Not enough to be worth spending your summer reading something you'll have to re-read later.
If you do any prep, I'd recomend what was suggested earlier - look at the syllabi for your classes or look a summary of the topic (wikipedia has good ones for all the 1L classes) and get a good grasp of what appear to be important terms. Besides, if you have any friends or loved ones, you should be enjoying what time you have with them now. I literally spent more time with my legal writing partner than I did my wife during the spring semester. Don't waste your summer doing something that will be, at best, only marginally beneficial.
As a compromise between recreational and educational reading, I'd suggest The Brethren by Bob Woodward.
If you're really curious, give the E&E's a shot but I wouldn't put too much effort into it (or at least, I wouldn't get stressed about it). I read PLS right before classes started last fall and got all freaked out that I hadn't spent the last 3 years preparing for my first week of law school. Turns out, it wasn't too big a deal.
It's true that as a part-time student working full-time you'll have much less free time than the day students, but it's still managable. Plus you and your fellow evening students can all bond by rolling your eyes at each other when the day students complain about how busy they are.