I just looked at the tickets... the regular adult & child admissions look about the same, but what's new is the discounted "young friend" ticket for ages 18-29. That's a good idea, because that's the age group they need to draw in for returning visits and PHS membership. They've never done a senior discount. Membership discounts are worth considering, especially for 2 or more people
IMO everybody should go at least once. It's spectacular. There was a book out a few years ago with a "bucket list" of 100 things -- and this was the only garden thing on the list. Both ticket price and crowds are similar to a day at the national aquarium... that's just the way it is. Remember that this is PHS's main fundraising event... nobody is raking in profits on the ticket sales.
The bus tours are usually a good deal but are limited in terms of time spent at the show.
Longwood Gardens, Winterthur, and Mt. Cuba are all within a stone's throw of one another... always wanted to do a long weekend and see all 3! I've seen them separately, and yes, they are awesome!