Hello Everyone
I am back home, and very glad for it. Going is wonderful, but coming back home is great. I've been really out of the loop during my 4 weeks away, so I'll conveniently pick up here, treating today like it's day 1.
Lily
Working out on the sand at Cancun is both good for your fitness and good for your soul. I hope you and Ted had a great time, and I assume you are getting stronger every day.
Diane
I'll answer your last question first. Yes, it's okay to run 4 days a week and cross train once. Actually it better than okay, it's a really good idea. Mix up running with biking, some weight or strength work, and some type of stretching work, and you'll see lots of improvement. Running all the time will increase your likelihood of injury, while varying your workouts will allow you to get fitter while remaining fresher, both physically and mentally.
There are only 2 hills on the January Disney Half marathon course, in miles 11 and 12, both overpasses. My understanding is the Princess Half marathon next March will start in the NASCAR track, then go through the second half of the full marathon course. This means the hills you'll see are the same ones as the (sadly departed) Minnie 15K course, 2 overpasses in mile 7, the up and right ramp in mile 10, and the tiny bridges (well they're not so tiny when your legs are blown) between the Boardwalk and Yacht Club, past the Beach Club, and between England and France in EPCOT. So effectively hill work really isn't neccessary for a good half, as you won't face much in the way of hills.
Having said that, some type of higher intensity work is important if you want to push in a half marathon between 2:20 and 2:30. This needs to be a bit harder than your typical training runs, as it trains your body to run harder and still relax, and trains you body to recover from the harder work.
You can do this intensity work in many ways. Hills are always good, drive up them a bit faster than typical pace, and you get the dual benefit of a bit more speed and the hills. Track work is good too, it's flat so no hill benefit, but you can push your pace a bit more and train your body to deal with the stress. Fartleks also work, plus they are among everyon'es favorite running terms

. Fartlek means "speed play" so you are running along at typical pace, then you open it up for a distance. Pick some landmark up ahead and run harder to the spot, then ease off and recover.
The key to all of these is they train your body to cope with a higher level of effort, so (1) early in the race your easier race pace feels like you're floating, and (2) when you are out in those last few miles and your body is under stress you've already trained it to deal with it.
A longest training run of 20K is fine for a half, which is 21, 098 meters. Oddly enough your body will tell you when you go past 20K (hey, we've never run this far, no fair), but you can drive in the last 1000 meters, particularly if you've done some hard training.
And lastly, don't do hard training too often, as it increases the chance of injury. 1 hard effort every 10 days or 2 weeks is enough to be sharp.
I got home Friday evening, so with the time change I've been up really early and in the fitness center the last 2 mornings, the true start of my Tower of Terror and Goofy training. I managed to strain my left quad 2 weeks before the Minnie 15K, but it's not wanting to heal completely. The importance of weight work was made very clear to me during my travels, as I did tons of walking but never got into a weight room. I assumed the walking would allow the quad to rest and heal, and that was false. I found the quad actually hurt every night, as I was walking a lot but never strengthening the darn thing.
So yesterday's #1 workout was lots of weight work and 8 miles on the exercise bike, and today's #2 was 11 miles on the bike. Amazingly, the quad feels much better after hard weight work and hard bike work than it did when I was walking. I've learned another valuable lesson; I need to do the weight work all the time if I'm going to run and stay healthy. Without the weight work my legs lose strength, and my dumb muscles begin to strain and hurt.
Man this getting old isn't that much fun. I used to just put on my shoes and take off. Now I have to carefully balance my workouts, otherwise my legs want to fall off.
Happy father's day to all. The title of father is one of my two favorites.
Craig