I think it's possible to survive a giant attack without being sent to the stratosphere, if you're moving (strafing) and you have enough armor rating for your level.
As a good general rule first I'd double check that I have the best weapons and armor for my level. If you're not smithing or enchanting check the merchants for better enchants. Level scaling can sometimes make encounters very frustrating.
With this in mind you could look into perks and enchants that work well without you having to stay toe to toe all the time:
- Absorb Health is very helpful. I have a Glass Mace with +15 Absorb Health and it makes dragon fights much easier. Even one that I enchanted myself with only +5 Absorb Health to have at least 50 charges was very helpful. No need to gulp any potions. It seems that landing a critical hit gives you more health in return (I've had sometimes much more health left than expected at the end of a fight, which I assume was related to the critical hits, maybe someone else can confirm this?).
- Get the Critical Charge perk. Land a power attack while sprinting, then keep sprinting past the giant, while your Absorb Health weapon keeps you in shape.
I also prefer to fight toe to toe, and don't want to use tricks related to pathing. But with that said, nothing wrong with softening up your giant with a few unsavory arrows (perhaps coating them with a health or stamina regen poison), until they are at close range.
EDIT: Well I confirm this works although I suspect they are also much easier past level 30. Got hit a few times for ~20% health damage. Used Critical Charge, then ran while casting the quick healing, then turned back, rinse-repeat. At level 38 it took 4-5 hits.
If you really want to stay in melee I guess you could try a Health Regen potion plus a max health increase potion, best armor and weapon available + smithing improvements... but if you run you can take two giants at once :)