On memorials: I completely agree that they should be unobtrusive, if present. We had a wishing tree at our wedding (not for money, it's a Dutch version of a guest book). Next to the tree we had a framed bridal portrait of my grandma, who was big on her traditions.
My best friend and I got married within 3 weeks of each other and were each other's MOH. Her mom had a super snotty friend at the (I thought nice) bridal shower we threw her... friend snidely informed me that HER DIL-to-be's MOH had taken all the girls in the wedding (including moms) on a Mexican spa vacation. While that sounds awesome and there is nothing wrong with it, the delivery clearly implied that our shower was totally lame by comparison.
In addition to Spa Lady, my friend's new SIL had very specific ideas about how to memorialize her mother, who died from a long illness about 5 months prior. SIL wanted a large portrait on an easel placed up front, like, next to the pastor. And her photo on all the programs. And an empty table seat reserved for her at the reception.