Obviously, Express Pass is the only way to see everything, so if you have that, you should be all right (though expect decent waits even at the express lines). But if you don't have your express pass and you don't feel like spending the $60-80 additional to get one, here's a quick guide to what you MUST see and what you can probably get away with skipping.
All the Scare Zones are worth seeing this year, and since you have to traverse them to get to all the attractions, don't worry about going out of your way to see or skip. The best one is probably 7, which features temptresses and their minions displaying the evils of the Seven Deadly Sins. The makeup and costuming are pretty spectacular, so if there is a must-see Scare Zone, this get my vote.
There are only two shows this year -- Death Drums and the always-packed Bill and Ted's Excellent Halloween Adventure. Here's the reality: if you want to save time, skip the shows. You'll wait not only to be seated (in a massive cattle-call crowd, no less) but the shows themselves run 45-60 minutes, which is valuable house line time. Fans and HHN regulars will be loathe to miss BIll and Ted's, since it has become iconic for the event, I know, but in my opinion, the show isn't what it used to be (though this year was funnier than the last few). Time is better spent trying to get to the houses.And now, the houses. First things first -- if you must skip a house, don't bother with The Thing. I am sad to say it, as this was meant to be the flagship house for 2011, but it somehow lacked the panache of most of the other houses. The scares were few and far between and the theming was somehow basic. Make this house last on your list and only bother if you have the time.
The Must-See of the year, however, goes to Winter's Night. It's the best of the houses, from actors to atmosphere. I went in three times and got more than my share of scares every time. It's beautifully presented, with loads of places for actors to hide. The creep factor is off the charts, so massive kudos to the designers for this one. Winter's Night is not to be missed.
The second Must-See is The In-Between. This is the funhouse for 2011 and it's delightfully disorienting (be warned if you have dizziness issues, though). You'll feel slightly lost from the get-go, so when the scareactors pop out from parts unknown, the shock is twice as strong. Don't trust your eyes, watch your step, and enjoy.
Here's a run-down of the rest of the houses:
The Forsaken -- It's skippable if you're pressed for time, but the theming and effects are well done. Horror buffs will dig it for that alone.
Nightingales: Blood Prey -- Great costumes, nice scares and strong theming. This is likely the goriest house, and the squick factor is high, so the easily grossed-out might not be too comfortable here. But for everyone else, do it. You won't regret the time spent on line for this WW1 house.
Nevermore: The Madness of Poe -- If you're a fan of the Grand Master, this is an absolute must-see. The nods to Poe's life and his descent into drink and madness are fantastic. This is perhaps the most subtle house, more creepy than scary. The atmosphere will get you; it's encompassing and electric. It's well worth the time.
Saws 'n Steam: Into the Machine -- I was expecting this to be the goriest of the lot, probably because I connected it to the Saw film franchise. This is more steampunk than splatterpunk, so it wins for decor in many ways. This house is LOUD. For some, this will add to the atmosphere; for others, it's just annoying. My group was split on this one. It was good, with some nice scares, but the loud factor was a bit distracting. Skip? See? I honestly don't have a call on this one. Poke a few people who are on their way out and make up your mind that way.
HR Bloodengutz Presents Holidays of Horror -- I wanted so much more from this house! The external theming was great fun and it really built things up. But the house disappointed. For one thing, not enough actors. For another, the scare spots were obvious and easy to find, so the jumps were few. The theming remained excellent, with possibly the most cohesive storyline. But this was also meant to be the comedy horror house, and I neither jumped nor laughed. It's skippable.
Rides will be open during the event as well. Jaws is great fun at night, so if the line isn't long, give it a try. As for the rest, it's nothing you can't see during the day, with far shorter lines. If you have time, they're great. If you don't, they're open all year, so don't worry about them.