Only at the big tech companies in the Bay Area will you get a hefty bonus, and typically generally mainly in the Valley in particular - startups generally don't pay that (occasionally you might find a startup that does 401k match though).
I haven't been at my BigCo long enough to say how much a bonus is like, but I do have max 401k match at 3% of my salary (rises up to 6% given time), which alone turns out to be ~$5k. Employee stock purchasing program with 15% discount with 10% of my salary maxed out also turns out to be ~$25k in stock (savings of ~$4k) - this does not include whatever benefits might come out of refresh stock grants, or performance bonuses. $50k in extra benefits does sound quite attainable though, even for an engineer not on $200k base at a BigCo.
YMMV of course.