My wife and and another couple are coming to London the last week of march and we are wondering from a natives perspective where is a good place to find a reasonable hotel for 6 days?  Anything under 120 usd per night with wifi, I know I can search Priceline but I'd feel better getting info from people who actually live there.  Also who has the best prepaid SIM card deal, all I really need is internet so I can navigate and look stuff up.  And finally what is local law in regards to small knives?  Nothing dangerous looking but a simple folder

Stay away from kings cross at night, watch your wallet/ phone if you go on the underground.
Dont stop and help anyone it will be a scam.
knife cant lock in position or be longer than 3" i think.
Go on trip advisor for hotels / b & bs.
I brought a tomtom with world wide maps for when i go to the states.
Most of the sim only phones are the same.
Im me if you need any help
Atb
Mart

Check out the Victory Serviceman's Club or The Union Jack Club. I'm not sure about the requirements, but I see you are/have been in the Military. From what I heard they offer nice rooms for about $60 for current (and maybe former) Service Members. I've never stayed there. You will have to fill out a membership form and jump through a couple hoops to make a reservation. My trips to London have always been last minute, spontaneous visits, so it wasn't worthwhile for me. I think I tried booking at The Serviceman's Club one time, but they were booked up for the next month, so book early.

ETA: Three (phone service) has decent prices for prepaid sims. The card is £10 and you get 3p/min calls, 2p/text, and 1p/mb. p: pence = 1 cent

(I'm from Utah. Obviously not a Brit.)

We went with my two oldest kids in June. We stayed at the Holiday Inn Express in Hammersmith. It was about 1/4 mile walk to the closest underground station. It seems like we paid around $100/night, and it had Wi-Fi and a continental breakfast. 

I bought a 3 Sim card for my unlocked Motorola smartphone. There are 3 stores everywhere. I bought it in Edinburgh and it worked everywhere in the UK, as expected. Data plans were much cheaper there. I'm sure I had some minutes and texts on the plan, but I didn't use them. 

You're not planning to drive in London, are you? Don't do it. The traffic, left-side driving, and congestion fees will kill you. Get an Oyster card, load it up and take the underground everywhere. It works great.

We arrived from Edinburgh at St. Pancras/King's Cross. No problems there, but we weren't there at night. 

Stop by Grosvenor Square. It's right next to the US Embassy. There are two really impressive statues there. 

I also went to the showroom of Holland & Holland (as in 375 H&H Magnum). They had double rifles and shotguns in there that cost way more than I make in a year. I did make one purchase. A baseball cap with the H&H logo. Only thing in the store that I could afford.

I didn't bring any knives with me at all. 

Felt naked the whole time.

Premier inns also cheap and clean places.
Dont bother with a car, use the tube or busses.
Atb