i don't know anyone who has a "mom" or "dad" tattoo - i know LOTS of moms who have their children. hmm. maybe that's an indication on the turn this society has taken...lol. that's a whole other discussion....
anyway, i have my son's name, and i have one that represents my siblings and my mom - so i guess i kinda do have a "mom" tattoo - but it doesn't say that lol.
one is on my hip, the other on my shoulder blade. i can't really answer which was more painful - the first i got on my hip, before i had a child, young n' dumb and all that - he did it for free, after hours, so he was kind of taking his time, doing lots of shading and having fun with it - he stopped after an hour because the tears just started gushing down my face lol. i wasn't even "crying" really - i held it all in and did great - but my body was just "done" lol. WUSS!! :P
my S. one, i got on my shoulder blade, and i was a trooper ;) BUT it was only lettering with some stars around it, with very little color. and it only took about 45 minutes. so there ya go :)
i think the point is that if it is meaningful enough to you, then you do it. it's worth the pain. i can't stand the stupid tattoos that mean nothing - and i won't get another one unless i have another child.