Regarding the golden circle route , I am planning to round Pingvellier National Park / Strokkur / Gullfoss and kiv Kerio crater in a day
( stay overnight at Gullfoss Hotel )
Did you visit Kerio ?
Was it a little too far off ? ( I cannot seem to locate it too well on my GPS iceland map

)
Also, there was a popular Nesjavellir Power station that if along the way I might just drop by and look see look see
Ryan
Hi Ryan,
First of all, Kerið (pronounced as Kerith) is on route 35 between Selfoss and Reykholt (more towards Selfoss). Its bang on the route 35, so you can't miss it. When I went, everything was snow covered and I was quite disappointed. I was hoping to get pictures like I had seen on the internet of the blue crater lake etc.... In August, you should get lovely views of the crater lake and the surroundings.
In terms of covering all the places you mentioned, it really depends on the route that you will take to drive.
I suppose you will head out east from Reykjavik and then head north-east on route 36 to go to Þingvellir. From there you will take route 365 to Laugarvatn, which then becomes Route 37 to Geysir/Strokkur and then to Gulfoss and then overnight at Hotel Gulfoss . In which case, you will not hit Kerið.
You do have a choice to not take route 365, and instead continue south on Route 36 after Þingvellir, and when you hit route 35, you can turn left and head in a north-east direction. Then you will get to see Kerið (it will come to your right side if you are heading north-east on route 35) and if you continue on Route 35, you will then meet Route 37 just before Geysir (around 12 kms before Geysir). This detour will easily take you an additional 2 hours or so, including time spent at Kerið.
I do not know what your plan is after Gulfoss. Are you heading south towards Vik ? If yes, then after visiting Þingvellir, you can do the route 365/37 to Gulfoss. And on your way to Vik from Gulfoss, you will anyway have to drive on Route 35 to Selfoss (unless Route 31 and 30 open up, in which case you will bypass Selfoss altogether...)
Hope this doesn't sound all too confusing... If you need any help, just lemme know...
I didn't go to Nesjavellir Power station. If I remember correctly, my friend had read something about the visitor's centre there being closed around the time of our visit or something like that. I didn't bother to check its location either, so can't really help on that one...
Cheers...