Hi CathyM,
Casa de la Judería is very nice. Tell him to also look into the Alfonso XII--I know, I know, it´s a palace, but it is owned by the Westin hotel chain and he might be able to get a good price on a room if he looks for deals. It's so romantic and so beautiful and the location is perfect!
There's also a hotel on Avenida de los Reyes Católicos right near the puente de Triana called Hotel Puerta de Triana. I've never stayed there, but I've walked by tons and it looks nice. A hotel on the same street that I CAN vouch for is Hotel Bécquer, and I believe it is in your friend´s range. Both of those are also in an ideal location, central and near Triana and the River.
There's also Hotel Inglaterra in Plaza Nueva which I love. My study abroad program used to hold its orientations there. They just remodeled it and it looks lovely.
I hope this helps! I can't believe how much info I just spewed out about hotels in Sevilla considering that every time I go there we stay with my husband's family! Go figure! I guess I've had to scout out locations for visitors before and have stayed in a few myself...you know, for those romantic nights alone...
¡Saludos!
Sarita