From the wikipedia page, it seems that coffee has a lot of good long term medical benefits, with only a few long term side effects if consumed in moderation, meaning less than 4 cups a day.
(http://en.wikipedia.org/wiki/Health_effects_of_caffeine#Long-term_effects)
This includes possible reduced risk of prostate cancer, Alzheimers, dementia, Parkinson's disease, heart disease, diabetes, liver disease, cirrhosis, and gout.
It has also been taken off the list for a risk factor in heart disease, and acts as an antidepressant.
Caffeine is not the cause of all of these positive effects, because there are some that decaffeinated coffee also helps.
Risks include increased heart disease from non-paper brewed coffee, iron deficiency, and anxiety.
Because of this, I'm considering deliberately drinking coffee, despite not needing it in order to stay awake. Are there reasons not to that LWers know about? Or are there other substances that have similar effects?
You might also take into account any possible downside from becoming caffeine dependent, ie unable to function optimally without it once you've gained tolerance. Caffeine dependence goes away again pretty quickly if you abstain though, so you can undo that if you don't like it.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.