*Short answer*
I brew 5 and 10 gallon batches - the large batches are split between 2 fermenters. I prefer to make one large starter, step it up as needed, chill it, decant most of the liquid, swirl the yeast so that it's more evenly distributed, and finally, pitch it. I use 1 gallon glass carboys cause I haven't felt like ponying up the cash for 5000 mL flasks.
*Long answer*
The style of beer will impact the size of your starter and the process of stepping it up. You say that you like to brew big beers - high gravity worts obviously require more yeast, and doubling a 5 gallon batch means that you need to double the yeast. So if you were going to make 10 gallons of imperial stout, your starter might need to be a couple gallons. You'd need something like a 3 gallon carboy to keep it in a single vessel - it might be easier to make separate starters at that point. Alternatively, you could begin with a single starter, split it into two vessels, and continue stepping them up. (I've done this.)
A stir plate would be super helpful for boosting your cell count if you don't have one. The increased cell growth would significantly decrease the required starter size. I use an old one from a bio lab that I bought on eBay - if you go that route, just make sure that it's been tested with a stir bar or paper clip by the seller.
Lastly, it's worth considering that multiple steps can produce more yeast than a single step. For example, making a 1 liter starter, decanting, and then adding 3 liters of starter wort should actually yield more healthy yeast cells than a single 4 liter starter. There are calculators online to help with estimating cell counts, starter steps, etc. Some are more accurate than others, but given that most homebrewers aren't actually counting yeast cells, it isn't an exact science anyway.
*The End*
