I'm confused... do you not currently have an HDHP? Or are you just considering increasing your deductible?
I think a good rule of thumb for maximum HSA savings is pretty formulaic. If D is your deductible, E is current year expenses, and S is the amount you can comfortable contribute in a year, then your maximum account balance should be 3D-S-E, but not less than 2D-E.
If you follow this formula, it essentially creates a situation in which you'll never pay post-tax dollars. If you had a one in a million accident in which you were admitted to the hospital on December 29, and stayed for a week, you could probably expect to be meeting your deductible for two years in one fell swoop, so to be totally 'risk proof,' you want to be able to cover whatever's left on this year's deductible, and 100% of next year's. Then you want to be able to re-activate your contributions next year, and be able to cover your deductible for the year after by the time New Year's rolls around.
So, to use my current numbers, I have a $3000 deductible, and a little over $500 in medical expenses so far this year. If my comfortable contribution rate is $1200/year (relatively low), then I'll want:
3D-S-E
3(3000)-1200-500
$7300.00
This way I could totally blow through my deductibles for this year and next year, and still be saving at such a rate as to be able to meet my deductible in 2015... Of course, that rate of savings wouldn't leave me prepared for 2016, but the odds of hitting my deductible 5 years in a row (we did last year) are pretty low, so I'm not gonna let that stress me out too much.
If you can't save your whole deductible in a year, and you expect to hit it with regularity, I would say just keep putting the money away, because it's better than the alternative. But if you're confident in your ability to recoup any costs, 3D-S-E leaves you practically bulletproof.