Gatwick to Marriott County Hall travel options
 

I've just read Ben Haines' advice (in a different post ) for using Thameslink from Gatwick to London Bridge to Charing Cross and then a taxi to a hotel.
It got me wondering if this route exists :Thameslink from Gatwick to London Bridge to Waterloo ? Or is there a Thameslink that travels from Gatwick directly to Waterloo?
The final step would be a taxi to the County Hall Marriott.
Is the Gatwick Express to Victoria + a taxi to County Hall route less hassle and time consuming?
Time of travel would be a weekday morning during rush hours, there would be three adult travelers and the amount of luggage would be one suitcase and one small tote bag for each traveler.

Gatwick Express to Victoria; taxi to Mariott would be the quickest and offer the least hassle. You can do it cheaper, but I doubt you can do it better.

The cheaper, but perhaps not better option mentioned by vcl, is South Central train from Gatwick to Clapham Junction and South West train from Clapham Junction to London Waterloo.

Thameslink stops at London Bridge then turns north. There are other trains every couple of minutes, usually from the other side of the platform, to Charing Cross: all stop at Waterloo East.
From Waterloo East it's a pleasant and entirely traffic-free walk, through the main station, to County Hall, though if you're unfamiliar with the area it's easy to get lost and have to deal with very busy roads. If I had no luggage, I'd walk it to wake up after a transatlantic flight. With luggage it can be a real pain, and you have to trek a fair way to the main Waterloo station (or stay on the train to Charing X) to find a cab if there's just too much luggage to cope with. If you haven't a good map of London handy, go to multimap.com, input the hotel postcode and navigate to see the geography of the stations.

Ben's suggestion is probably the best, though other routes are hardly going to kill you.

For my part, with luggage, I should change at London Bridge (on the same platform), go through to Charing Cross, and take a taxi to the Marriott. This time the driver will not complain of the shortness of the journey. Without luggage I should indeed leave at Waterloo East and walk right through the station to the Eurostar exit near York road, but with luggage, and with a budget that affords the Marriott, I should taxi from Charing Cross.

Still not from Victoria, a longer run.

I am afraid there is no through train from Gatwick to Waterloo, and Clapham Junctioin is a vast station, biggest in Britain, and a truly nasty place to change with luggage.

Ben Haines, London

It's got to be Gatwick to Clapham Junction & change to a train to Waterloo. A simple five minute walk via the footbridge to county hall.Use the London Eye as your guide

Thank you all for sharing your knowledge.
Two of the three travelers have been in London several times and have used the Gatwick Express + taxi to our hotel destinations in the West End.
This trip, since our hotel is on the South side of the River, we were just exploring other options to get there during rush hours.