I came back last Saturday after a wonderful 3 nights vacation in Istanbul.
Thank you All ... very very much for your helpful guidance -- without this I would not have ventured out.
Here is my trip report :
- cancelled by United ticket from IST-FRA-SFO .. took credit for future flight (Thanks United for this option)
- walked over, got visa on arrival. Took me 5 minutes !! ... and $30 USD cash (they don't accept credit card - not sure about other currency)
- collected my checked 23kg bag and found 'Left Baggage'. Cost : $5 USD/day or 90 TL
(Kudos to IST airport -- it was so convenient)
talked to touristanbul counter - they put me in 'The Grand Yavuz Hotel' in Sultanahmet area
(Hotel was fine - nothing great, nothing bad either. Decent breakfast, helpful staff. One downside - this is a very hilly area, lots of steep walks up and down. I'm glad I took my smaller bag with me)
they also got me into HavaIST bus to Aksaray and gave me directions: walk few minutes to Aksaray T1 tram line station to Cemberlitas (3 stops away), and from there walk 10 minutes to the hotel. (Cost : HavaIST shuttle : 87 TL ~ $ 5 USD, and got a 10 pack istanbul public transportation card for $20 USD - good for travel on bus, metro, tram, ferry, funicular, metrobus, marmaray
This card made my transportation very convenient all over Istanbul)
next 2.5 three days, I went around Istanbul - Aya Sofia mosque, Blue Mosque (which is closed), Grand Bazaar, Spice Bazaar, Taksim square, Galata Tower, walked across the Galata bridge, visited Topkapi Palace and Dolmabahce Palace - did not go inside as it takes too much time to really visit, .. went to Kadikoy neighborhood for another afternoon/evening. It was fun -- Istanbul is a very charming place to visit. Not to mention, Excellent food all over ( vegetarian or non-vegetarian options ), lovely Turkish tea with Turkish sweets (baklava, halva, etc)
On Saturday, took a taxi from hotel to IST airport : took 1 hr 15 minutes (cost : $30 USD). I could have gone via public transportation, but did not want to risk delays as I had to pick up the Left Luggage.
Getting my bag back from Left Luggage was smooth.
They have made IST airport and facilities really wonderful .. so convenient.
Lastly -- I found Istanbul quite safe, I was walking around with my phone out using google maps, and there were many others like me. Shopkeepers at the Grand Bazaar and other places were quite nice .. did not feel any undue sales pressure. Language was a slight barrier, but everyone tried to help.
Thanks again everyone for your help - Hope my report helps others plan their visit.