Here’s the scoop. I’ve been saving up for a couple years for a trip to WDW and UOR. Kids are 13, 11, 8. Goals are low crowds, low wait times, value/fall pricing, good weather. Not interested in fireworks, parades, characters or special events (would like to avoid these, actually) - mostly rides. We figured from a BUNCH of research we’ve done over the last couple months (from too many websites to count and tons of opinions) that January would be a good time (still worried about ride closures - does UOR have annual winter closures like WDW? Are their water rides open? Are resort pools open?).
We avoided the Celebration of Harry Potter to avoid crowds and are currently reserving hotels for UOR 1/19/17-1/23/17 and WDW 1/23/17-1/29/17. We were hoping to take a trip before our oldest is in High School as pulling kids out during the school year and staying caught up gets more difficult then (that would be August 2017), but aren’t totally opposed to it. Because of cost, this would VERY LIKELY be our only trip to that area (we live in AZ), so we want to get it right. A BIG draw for us is UOR with the Wizarding World of Harry Potter and 30 minutes is a long wait for us to ride a ride, IMO, which is one reason we will be staying at the Hard Rock for the Express Unlimited Passes.
As I’m reviewing the crowd calendars for January, they seem high but still recommended as some of the best weeks of the year (particularly for UOR at 7/8), though September and parts of October/November/December see significantly lower crowd numbers (3/4). I just want to make sure for my 10K investment that we will have low crowds and smooth touring without surprises. My tentative touring plans show all waits at UOR under 12 minutes (assuming because we are using Express Unlimited and ending well before park closing) with a random Pteranodon Flyers at 33 minute wait (probably skip that) and an odd 44 minute wait for the Hogwarts express one day around 3:45p (maybe it only runs every hour?) Wondering if crowds at Universal always have a higher crowd level because there are less parks and less acreage? Or are they rated differently? Sorry for the novel, but any input is appreciated. We are nothing if not thorough when it comes to vacations.
If you have the Express passes I wouldn’t worry too much about the crowd levels, with HP I would make use of the early opening you have staying on site and ride the most popular first ie Hogwarts Express, Gringotts, Forbidden journey.
I would suggest Fall might be the best time to go, slightly lower crowds, cooler weather and you can experience the Halloween decorations etc. We are going Fall 17 and have been before at that time and would really recommend it not just for Universal but for Disney too.
We are not big on parades/ fireworks etc but we have done MNSSHP before and had a brilliant time and are going to book it again for next year.
I do understand how important it is to plan, as we only go to Disney every 2/3 years or so and it is pretty pricey, so it’s good to do all you can before you go.
There are guys here who go much more frequently than me (and know so much more!) and they are always willing to help out with any questions 
In reply to your specific questions Uni hotel pools are open. The water rides get closed for refurbishments but they rotate that so at least one is open. Universal has low crowd levels in Sept and Oct due to parks Closing at 6 pm on 5/7 nights for HHN. Jan can be too cold for swimming though. Whatever you do you will really enjoy it.
Ps you are aware exp pass not valid in some of wwohp.
Thanks for confirming about the pools yes, I’m aware is the few restrictions on the express unlimited passes. Good to know at least one water ride should be open (they are some of our favorites). I didn’t think until now to ask if Universal also closes rides down commonly in January for rehabs. Do they? Is there research or stats on that somewhere? Also, I believe the pools are heated, so my kids will swim in them anyway - their crazy about them! Thanks for the reminder on the HHN nights. I totally forgot that. Makes sense that the crowds would be lower that time of year then.
I’m looking heavily at the week before Thanksgiving as an alternative. With Universal over the Veteran’s day weekend in 2017 and Disney following up until 11/18. Crowds at Universal are reduced then, and Disney’s are somewhat comparable. Flights are cheaper for us that time of year, but hotels look more expensive (though I believe Disney usually offers discounts on them starting in April or something).
Are there any special events that period that would cause conflict? I’m aware of the holiday overlay at Disney and the Mickey’s Christmas Party. I was thinking there might be a marathon or something. Maybe that is earlier in the month.