Fiji is perhaps a little behind, when it comes to internet options. It's only in the last couple of years that it has become more affordable, reliable, and with faster speeds. Even so, you will find service to be patchy or even non existent in the more remote areas. However, most of the main tourism hubs and resorts have high speed internet, with wi-fi becoming more common.
There are several internet booths available in the airport (that I'm aware of). For those arriving, go to the domestic terminal, and there is a small internet cafe. Prices aren't cheap, the last time I used it, the cost was fj$5-6 for 30 minutes.
There are also some computers in the departure lounge, for those of you who are leaving. Prices are the same, fj$5-6 for 30 minutes. The slightly annoying thing with these, is how often you purchase a dud card. For me, I found it to be a roughly 50-50 chance. So you have to go back to the shop, wait in line to get it changed, and hope that the new one will work.
Thankfully, the airport does have wifi, so if you have this then you can forget about using the public computers. The wifi covers the whole airport, and will work with any of the pre purchased cards.
All of the main centers have a decent range of internet cafes, with lower prices than you will find at the airport. Nadi, Denarau, Lautoka, Sigatoka, Pacific Harbour and Suva are some of the main centers along the south coast of Viti Levu.
The main resorts all have internet...some of them also have wifi. For example, Robinson Crusoe Island, where you can purchase a wifi card, which is fj$20 for your entire stay.
Wifi is becoming more common - up until recently your only option was to use the computer in the resort lobby. Slow connection, usually a queue of people wanting to use the single computer, and the costs were ridiculous. This is still the case in some resorts.
There are wifi hotspots all over Viti Levu now, so a standard wifi ability on your phone, ipad etc will probably be enough for you. However, if you want more coverage than you get with standard wifi, either purchase a 3G Flashnet stick, or bring one with you. That allows you internet access anywhere that there is mobile phone coverage.
There are two main providers for mobile coverage in Fiji. Vodafone, and Digicel. However, until recently it is our understanding that only Vodafone provided 3G, which is what you need to connect your laptop/ipad to the internet. Another advantage of using Vodafone is that they have an office at the airport, so you can get yourself a sim card and/or USB Flashnet and be setup as soon as you arrive in the country. Inquire at the Vodafone office in the airport when you arrive, to find out all your options.
We understand that there is now limited 3G coverage with Digicel around Viti levu. Find out more from digicel.
One option that might suit, is purchasing a USB Flashnet stick...and get some prepaid credit put onto it. This will work on a device like laptops or iPads, and gives you internet coverage anywhere there is cellphone reception.