As the days get shorter and colder, it is often hard to get outside during the week to ride. While there is no real substitute for being out on the road, I am looking at options to keep me in some shape over the winter months. I am considering spinning or perhaps getting a trainer. Any thoughts on plus or minus of either? I have done both, and they can be a little dull, but better than nothing. Opinions? What does everyone else do?

I run, strength train, use a trainer, and ride as often as I am able. Variety during winter works best for me.
However, so far this year I have been riding more than anything.

If you can, join a good spinning class 1-2 times a week. A good one won't leave you bored. Then suppliment that with rides on your trainer at home.

If your spinning classes are at a local gym or community centre, get a membership which allows you to use the weights, pool, etc. and make an evening of it when you go to spinning class. One place I went had an indoor track, weights area, and pool. I'd go a bit early, walk briskly around the track a few times, jog on the treadmill for a little bit, then do the class ... then I'd do weights and core work, a bit more jogging, and some more walking around the track to cool down. And I did that twice a week.

At home, I'd do commercial intervals on my trainer 1-2 days, and 1-2 days of longer rides either on the trainer if the weather was really bad, or outside if the weather was any sort of decent.

In addition to that, sometimes I'd throw in some cross-country skiing and snowshoeing.

And for years I kept up walking 2-3 km a day at least 5 days a week.

The best exercise is the one you'll actually do.

I have a Concept 2 rower, used it this morning, it's great.
Go used, odds are it will be hardly used.

I like resistance exercises, I have a TRX, and a ton of resistance bands.

I have a trainer, I don't like it, but I use it once a week.

You could do laps at your local pool, jog on a treadmill, whatever works for you.

You could even go to a gym and pump iron.

I have a trainer. It's boring, but it's got such a low "excuse level" that I end up using it. By excuse level I mean the number of possible excuses that might prevent me from doing it... for example "it's cold outside", "I don't have time to go to the gym", "I forgot to pack my workout clothes", etc. Having "it's boring" be the only possible excuse is hard to beat.

That being said, I like running, and I am able to run in colder weather than I would bike in. I also like cross-country skiing a lot, though that takes more time and planning (usually can't do it in the city).

Weights and spin class at the gym. Rollers at home. Skiing. I rather like the change-up that winter brings. Different things, different goals. It's a chance to recharge. IMO rollers with resistance beats a trainer. For me, variety in the winter is the best thing.

I don't ride rollers until winter gets a complete lock on my area; like 3' of snow and ice or more. Until that point, I jog, snowshoe up New England mountains and lift weights. I mostly can only ride on weekends. Sometimes I ride a well lit bicycle to the local track weeknights and do speed workouts or pliametrics there. Like someone else said; variety.

Hit the gym, ski (both XC and DH), snowshoe, run, indoor soccer. Do something, even if it's just knocking out a set of 6-count burpees during commercials.

skate - hockey, yes, we can skate in SoCal...
and a 90 min session of 'pickup' will fry most anyone...
it's a little tough on us geezers when you're on the ice with the younguns, but many of them can't skate...
...for them it's straight up the ice at speed - Rut Roh, boards are comin up... BAM!

skiin is a little more planned out...

I use a trainer when it's raining outside.

If you want an example of a motivated, disciplined cyclist have a look at 51 yr old, Kevin Metcalfe's workouts during the winter. He's on the trainer every day for 1 hr with longer rides on the weekends. Seldom takes a day off.

If you limit your trainer rides to 1 hr they aren't that bad provided you have some music to distract you.

A trainer is a very good investment - just a simple model, not the fancy computer controlled ones from Tacx. Put a movie or some music on and you are good to go for 1h-1.5h. Currently I am still riding outside and I do weight training 2x a week. When it starts snowing I am dusting off the trainer to substitute for my hours on the bike.

Spinning is a nice addition since most trainer workouts are steady state. A spinning class has a bit of everything squeezed in - tempo, resistance, etc., and is nice to see some people around every once and a while. =)

Good luck!

And I also recommend travelling ... take your bicycle to some place warmer for a couple weeks (or more!) mid-winter and get in a lot of cycling during that time.

Outdoor pickup hockey, beer league hockey, and a little more work with karate (flexibility). Plus, like counting cars around you, hockey makes you count jerseys - unless you see 5 jerseys from the other team you are about to get leveled. ;-)

Just picked up a trainer and I enjoy it...having music or a TV is a must but I am easily going 30-60m per day and am drenched/sore when complete; I feel I am getting a good workout.

I love snowshoeing, hopefully I get to use them this year. Other than that it's trainer, rollers and hot yoga.