30 is really small. go for the 36"

a few inches from the toilet isn't going to be a big deal.

my small bath is only 6.7 feet long, I have a 48" vanity, and still have 15" from center of toilet.

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If you'll have a separate linen cabinet, do you need a lot of vanity storage? Is this a secondary bathroom? I think the spacing around the toilet really depends on who you expect will be using it. If it's a kids bathroom, 15" is probably okay, but if it's going to be regularly used by grownups (especially men or larger women), you are going to want more space around the toilet. Our master bath has a toilet closet that's only 30" wide and my husband pretty much refuses to use it. I had to remove the tissue holder from the wall just so he didn't run into it. We're about to remodel and I'm allowing at least a full 36" for the toilet (and it' won't be in a coffin - I mean closet.

Thank you all for your comments. We are going to go for a larger toilet space and smaller vanity with a separate linen cabinet.