New Zealand advice

[Soab]

I know it's short notice but I'm flying to the South Island Boxing Day, will be spending 3 and a half weeks there. Few days in Nelson then 6 or 7 in hanmer springs. Have 2 guided days booked in Nelson then 2 more in hanmer. Sight fishing for browns is what I'm after, wondering if any one has advice or experience on which rivers to try on my own. Also will be heading south to wanaka. Thanks in advance