Attendance is not necessarily for your benefit nor for the benefit to the deceased but is more a means to show your respect for the person and to offer support and condolence to the deceased's immediate surviving family.
If that person's family are all JWs who will shun me, then I will not attend and accept being treated in that manner but I may send them a card to acknowledge their loss. If the person's family does not shun or if there are 'worldly' family members, I may then decide to attend to show support to those people.
A funeral/memorial service of any religious denomination will usually contain information I and many other attendees may not necessarily agree with. I consider that presentation is not really for my benefit as a non-family attendee but is usually intended to comfort the person's immediate family, so they will feel that God has received their loved one in heaven or wherever they wish to believe he/she is going. During the service, I generally reflect on the positive interactions I've had with the person while living.
If there are personal stories about the deceased, I will listen to those as they are often funny and reflect on the person's personality. I may offer a comment to the officiant on enjoying that part of the service.
The funeral service itself usually affords minimal personal interaction while a pre-or-post service visitation typically will allow more interaction with the family.