Training partner yes/no?

I do nearly 100% of my training solo.

My main issues with group training as a whole are that 1) rarely do my schedule and everyone else's schedules sync and 2) group training rides usually become a lowest common denominator type ride... which is great if you're one of the weaker links but it sucks if you're not.

Different strokes for different folks though.  I have always found group rides to be the worst workouts I have ever done.  I want to get on my bike and hammer.  I'm not there to ride 17 mph, I'm not there to stop 5x, I'm not there to socialize.  I'm there to work.  That's just how I'm wired.

I have a great running partner that helps me get out of bed - accountability is big for me personally.  I'm not nearly as amazing as Bob or Scott.  I've never swam with a group but can see how it would help.  So maybe half my runs, 1/3 of my biking and none of my swimming are done with others.  Joining a group can be helpful though especially on long bike rides.  Not only is it nice to have company but having an extra hand to help change a tire is nice as well not to mention I feel safer riding in a group than on my own.  Not sure where you are but you could try reaching out to a tri club in your area and see if you click with other folks who live in your area.  Might be a nice change of pace and you could make new friends.

Keep in mind a lot of groups are not  willing to accept people on tri-bikes (for good reason).  

My opinion either way though...Race solo, then train solo.

Tri groups will.  There is one for just about every area of Houston/suburban Houston.  OP says Woodland (I'm assuming The Woodlands) and OutRival is based out there.

Really?  Name a group, I want to know who to avoid.  Bike Barn rides allow tri bikes, Northwest Cycles allows tri bikes, all the organized bike rides I know of - Frost Bike, Katy Flatlands, Peddle for the Ducks, MS 150 etc.  I've ridden my tri bike in all but the MS.

Sure, you will find cyclists who don't want to ride next to tri bikes but I've never heard of one unwilling to accept people on tri bikes.

But like Scott said there are tri clubs all over Houston and while Out Rival seems to be closest to you there is also HRTC and Bay Area Multisport as well as the previously mentioned Cy-Tri.

I train with groups, or my wife, when I can.  But largely it is solo.

For the longer run/rides I try to hook up with the group to help push the pace and for safety / support.  But reality is that I work too much and my available training hours aren't always what works for groups.  Being reliable at work makes me somewhat unreliable as a training partner.

The other problem is finding a partner who has a similar pace to you.  I'm pretty darn slow for my AG, but generally faster than my wife.  For running it actually helps me a lot to run with her as she has much better pacing than I do. 

For swimming I try to swim with a class, but I have paid for a lot more sessions than I actually use due to life getting in the way.

My wife and I train together, she is just a little bit faster than me and that works out ok.
We also have a few "tri" friends we will train with about once a month just to have more people for long runs or long bikes. A few times we have invited people to go out to a lake with us and swim.

If you can find someone that is your pace and can train with you, I suggest you do it.

I do a little of both.  My swim workouts are for the most part, solo.  I have done a few master's classes, and do like the workouts.  But, if I can, I avoid crowded lanes in the pool.  That way I can concentrate on swimming, not on avoiding the person coming towards me.

For running, I run with a run club.  Works great for longer runs, with water stops, and nutrition support.

For biking, I do a combination of both.  Sometimes group social rides, and sometimes alone, or with one or two others.

So far, it's working for me.

^ This.  The only exception is I do swim with a masters group.  All my runs and rides are solo.  Group rides for me are only for recovery. 

I race alone.  I train alone.  

Although it would be nice to have someone other than my dog on an OWS.