In general, I would advise against using anything from the Epic Level Handbook for characters who are not higher than level 20. An epic D&D character can be so good at balancing that they walk on clouds, or so good at swimming they can swim up waterfalls. "Epic" isn't just a term to make it sound cool: using those rules, characters do things that only make sense in the context of epic poems and myth. So while there is, in theory, an attitude beyond Helpful in 3.5e, Fanatic, it should be used exclusively as the result of the actions of epic characters.
Setting aside the Fanatic attitude, any hypnotic suggestion that equates to a dominate effect is neither brief nor reasonable. The highest mechanical relationship in non-epic play is Helpful. If you hypnotize someone and say, "How about you obey my orders from now on," it doesn't matter how helpful they are, they'll still say no and probably be pretty offended. If your best friend in the whole world suggested such an arrangement, you wouldn't agree. Since the subject views the request in a friendly light, they'd probably laugh it off as a joke rather than shank you for trying to brainwash them, but that would be the extent of it.
The text "the creature retains its new attitude toward you, but only with respect to that particular request" just means that the guard who let you by won't raise the alarm once the spell is over, or the official who gave you an invitation to the duke's ball won't have that invitation cancelled as soon as you leave the room—it's there to make sure the subjects of the spell don't immediately undo whatever you've convinced them to do, and that's it. It can't ever actually change people's opinions of you.
