If you live in Texas and have a 3-5 year old, be sure to check out the Preschool Pass. I had to search for it on their website, it wasn't super obvious. I believe they have to her ordered online by a certain date and then activated by another date. It's basically free admission for them from now until September.
Do check their website and/or grocery stores. I know they had a deal on Groupon a few weeks ago, but it wasn't much better than the discount on their website. Also, if you are going multiple days consider a fun card and/or season pass. I think the fun card is the same price as a one day (non-discounted ticket). dH and I have one fun card (admission now through early septmber no perks) and one annual pass (1 year admission, free parking and discounts on in-park purchases). We've gone twice this year, and the annual pass has already paid for itself with 2 days of parking (was $20 last time we went - eek!) and the 20% discount on a few snacks/drinks.
They seem to be doing a LOT of work on the park. The Clydesdales/beer tasting are gone. The dolphin tank and coral reef are closed for renovation (to reopen next year), there's a newish pet show, and a new sea lion exhibit is set to open very soon. I think there's also a new lumberjack show, although it wasn't showing last time we went. We went once in February and once in April, both SUndays, and crowds were negligible - rides were pretty much walk-ons and we got to the shows 5 minutes or so before they started and were fine. I'm not sure how it is in summer, but we went a few years back and I don't remember any major lines or anything.
As others have mentioned, there are lots of shows on a set schedule, so you do need to plan for what you want to see. We usually just do a few shows and let the kiddos play in the Sesame Street area, but if you want to see it all in one day, you'll need a plan. They hand out schedules at the gate, but they also post them online, so you can figure out what you want to do.
They also have a waterpark. It's a ticket option/upgrade. We haven't been since it was rebranded/made a separate ticket, so I can't really comment too much. We went not back when it was included in the regular ticket, and it was fine. Nothing spectacular, but a nice way to beat the heat. I think they did some renovations/added rides, etch since they so maybe someone who's done it more recently can comment,