First timer questions
 

We are a party of 4 adults with 4 checked and 4 carry-on bags, arriving in Seoul for 4 days in early November. Sorry if these are covered elsewhere but I could not find the answers.

1. Any recommendations for round trip transfers from ICN to the Park Hyatt? We arrive on Sunday at 5:30pm and depart on Wednesday at 20:30. Any benefit for purchasing round trip?

2. Are we OK wearing business casual clothes for touring and visiting most restaurants?

3. Will weather for early November be similar to New York and other east coast US cities?

4. I have an unlocked i-Phone 6. Since we are going on to Australia for 10 days, I assume it might be best to just buy a pre-paid international plan through AT&T before departure. Any better options for limited cell phone usage while traveling?

As always, thanks for your help.

1. I would recommend using the Korean Air Airport limousine bus from the airport to PH Seoul. They drop you across the street of the hotel but very cheap and convenient for first time travellers. Would definitely be cheaper than Jumbo van taxi from ICN into Seoul. The hotel could arrange a transfer for you if you really want the Jumbo Taxi.

2. More than fine dressing business casual.

3. Yes, it will be cool and definitely jackets and sweater weather.

4. Renting a wifi egg at the airport could be helpful for you.

If you're looking for data, I agree that a wifi egg (wifi hotspot device) is a good option, particularly with 4 of you potentially that can connect off of it. If you actually need to make voice calls in Korea, you can tag on a Skype account/package.
I found pick up and drop off at the airport relatively painless and the device I was given was pretty small. My only suggestion is that you may want to get a USB battery pack to get a full day's usage out of it unless you're able to charge it midday.

the biggest battery pack you can get is a great idea but a lot of Korean cafes and restaurants have charging cables and/or plugs. They're so mobile friendly here.

I maybe going to Korea (Seoul) in July next year.....hope I still get unltd 3g via the TMO service I have here in the USA!

Our family uses T-Mobile; we used our phones in Seoul earlier this year, as you can read in past threads (Cellphone Plan Recommendations, S. Korea Prepaid 3G Data + Voice). I'm sure you can find others by searching.

I'd suggest that you make sure the carrier settings are updated on your phone before you go, and consider renting the Olleh Egg or some equivalent. You pick it up at the airport and return it later to the same place.

T-Mo Simple Choice Plan will get you free global data in SK, but it will be slow (maybe, it will be faster next July as it's over 7 months away ...) but for about $5 USD a day, rent the WiFi egg at the airport (arrival hall, landside - one of the service center is open 24/7) for unlimited 4G/LTE access.

We saw "5G" on our devices but obviously not connected to or using it - but, "ordinary WiFi were ultra fast, as in 75 MB up/down-load and at the Novotel that we stayed at, we got over 100 MB u/l and d/l speed, no that is NOT a misprint or typo, we've getting close to 115 MB u/l & d/l over hard-wired ethernet in our rooms - amazing (and, I setup my own TP-Link travel router w. the firewall ... )

Smartphone access over T-Mo was free but painfully slow, it was perfectly functional. But, for the daily price of a cup of Starbuck in Myeongdong, with a nominal & refundable security deposit - tethering enabled to share (up to 4 or 5 users) - I highly recommend the egg. Also, Skypass members flying on KE, upon presentation of the BP on arrival - sometimes ... get discounts & special promo on WiFi hotspot rental.

On departure/leaving from ICN, just drop that off at the 24/7 airport landside counter - and you are on your way. Best way to do this is to reserve it ahead of time - at least 3 days & everything will be set and ready for pickup on arrival. (That is, unless you will be activated on Project Fi with full data speed by next summer ... got my "Invite" already & weighting the pro's and con's)

Thanks for the Olleh egg suggestion! I just booked one for my trip in January.

Is it cheaper to rent an Egg or purchase a prepaid sim card for 3-5 days?

I rented the egg from KT Corp which was 5000W/day (if you reserve ahead you don't have to pay for the device rental, just the daily data fee). It's unlimited data so you're looking at 15000W to 25000W.

Conversely, you can get a prepaid sim. Per the PrePaid Data Sim Wiki, you're looking at the following 30day options from KT:
500 MB: 8,800 won
1 GB: 14,300 won
2 GB: 19,800 won

Thanks, I guess I'll probably go with a sim card then as 2gb is more than enough for 4-5 days....even with map usage.

As I'll be in Hong Kong the week before Korea, I can always pick up one of these

http://www.beecrazy.hk/en/deals/seou...-local-postage
S.K. Telecom / 8 days / 5GB data / HKD $150 ..... ~ 23,426 won

http://www.hk.chinamobile.com/en/cor...ming-data.html
7 days / 5GB data / HKD $155 / ~24,185 won / I can use remainder data in HK.