There are two things that I think would make premium so much more appealing to people...and to me:
1) Make it so that you pay for premium on your IP or selected range of accounts (or a mazimum number of e-mail addresses etc) rather than per account. This way people with multiple accounts and households with more than one neopets player would be far more likely to pay up, especially when there are kids. What parent would pay for premium more than once so that all their sprogs could be equal? Not many I bet, heh.
2) Half the price from $8 a month to $4 a month (and therefore from $96 a year to $48 a year). I predict that if they did that more than double the number of people would sign up - thus making them more money than they do currently. I'm a student and I can't afford what it currently costs, and I bet a lot of parents wouldn't fork out for that either.
If they did those two things I would sign up for premium in a heart beat, absolutely, and I would guess that far more than double the current number of people on premium or who want premium would sign up.
It would also be good to have a guarentee that they wouldn't auto freeze paying customers but investigate incidents properly before dealing with the matter. I'm surprised they don't do that already for premium users. MAybe being allowed to have more accounts too - and the ability to set them as secondary accounts - meaning you can't earn any nps on them so they've no reason to be suspicious.
So in short, I don't really want any extra items or bonuses that you don't already get. I want:
1) half the price
2) allow premium per IP/selected range of e-mail addresses rather than per account
3) extra insurance against getting unfairly frozen
and maybe: 4) a higher number of extra accounts that can be set up so you can't make np on them through games etc.
*phew*