We are regular visitors to LTN, and last year we flip-flopped between Ocean Sky and Signature.
Although they have prefab buildings as the FBO, Ocean Sky has a nice modern feel to it on the inside, but we felt they were lacking a little in terms of functionality, and having to move between two buildings in the rain to get to the OPS/FIN side of things was a pain. No complaints about the service though, very professional, and very helpful staff when it came to gathering information on accom etc. Our principal, however did not like Ocean Sky, and we have moved over to Signature full time.
On the Signature side of things, I agree that the building is dated and somewhat cramped if there are a few aircraft worth of crew and pax waiting in the lounge. I have to commend the service we get from them though, absolutely brilliant, no matter what the request. Great OPS dept who can do magic when required, and they really do have lovely ladies getting the job done at the coalface. For us it helps that they have GAC right across the ramp, and there seems to be good coordination between the two. Few places can turn you around in 35 mins on a tech stop.
We have not yet tried Harrods, so I cannot comment on that.
As for accom, we have tried all around the area, and Harpenden comes out tops for our requirements. We like the Harpenden House Hotel. Just off the main drag , and within 5 mins walk of 6-10 pubs, 15 restaurants, ample take away shops and Sainsburies. Good internet, spacious rooms if you stay away from the main building. Quick 5 min walk to the train station, and 25 mins into Kings Cross station. H-House also gives you access to Harpers Fitness, a two min walk away. A very very nicely set up health club with a serious gym, indoor pools, tennis courts, and lots of nice scenery.
- all included in the Harpenden House package. Harpenden in the summer is awesome, everyone is outside and the chilled frosties abound.