Essentially, the first thing to know is that you're only locked in to your cohort for the first year (though I believe you also get priority for evening or weekend respectively for future years), which gives you a chance to bond with that cohort group. There are other opportunities to bond/meet up with other cohorts, though it does take additional effort. In actuality, there are cases where people have switched cohorts, though it has to be with good reason and be requested/executed with the program office.
Choosing weekend vs evening really depends on your own needs and schedule. For example, many choose weekend because it has about half of its classes in the South Bay (Santa Clara), or because they are commuting in from outside the bay area. Others will choose it because they have dynamic weekday schedules (travel for work, or irregular hours due to workload, etc.). I chose it for the latter, given I work in consulting/services.
There are definitely events that happen on weekdays as well as weekends, so either way, you are bound to miss out on an event or two you'd like to join. It will really depend on the timing of the event itself. Still, there are so many opportunities for networking, speaker series events and otherwise, that more likely, you'll be looking to find time to squeeze any in during the first year (given the crunch of core class schedule, and your actual "work-work").
On the food side, lunch is provided to weekend students at no extra cost (class is all-day Saturday), whereas weekday students class starts at 6:00 and does not provide dinner (assuming you've already eaten). In contrast, weekday has a shuttle service from different locations, while weekend does not. Weekenders tend to carpool instead.
The last thing I can think of is that for the first-year, Weekend classes are 4 hours long (9am - 1pm, 2pm - 6pm) versus 3 hours for Evening (6:00 - 9:30pm, I think). These longer sessions can be grueling, but the added benefit is less sessions potentially-- I believe Winter break was a few weeks longer.
Can't really lose in either case-- I hope to make use of some weekday classes in the future myself, though I'm officially a weekender. As always, it's all about what effort you put into it really, rather than which cohort you join.
Congrats to Round 1 admits, and good luck Round 2'ers!