Dolphin House is actually Pimlico - pleasant enough and probably quieter than Citadines Trafalar (actually Norhumberland Ave) but I would go for the latter - on the doorstep theatre/restaurants/plenty of shops, cafes etc whereas Dolphin Sq is always a tube/cab/bus ride away.

At Citadines, you are a minutes stroll from the river and views of the London Eye and Big Ben; about the same time will get you to Embankment underground station. A bit longer (5-10 minutes) stroll takes you Covent Garden; Soho; Whitehall; the South Bank etc. It wins hands down.

I stayed at the Dolphin House several years ago when it was still the Dolphin Square Hotel. It's in a nice, quiet residential neighborhood and is just a couple minutes walk from the Pimlico tube station. A nice location, but there was not much around in the way of shops, restaurants, etc...

Thanks for the information.

I have stayed in this Citadines several times, great for theatre land/river etc you can walk most places and there is a little Tesco convenience store on the corner.Avenue not as busy as you would expect and you can always ask for a studio not facing it.

Here's my view on the Dolphin House that I posted back in March:

We just got back from Dolphin House yesterday (Sunday) after ten nights. We were very happy with it. Please feel free to email me with any specific questions but here are my general views on the place. Rented a 3 bedroom, 3 bath apartment with kitchen for me, the wife and 3 kids (9, 11 and 13). The apartment was spotless when we arrived. It looked like it had never been occupied before (wife was very pleased (neat freak)); everything looked brand new right down to the chaulking around the shower/tubs in the bathrooms which in our experience can be dirty looking and unpleasent even in upscale hotels. We had 3 king beds (this was a factor for us in choosing Dolphin House; many places we researched had only queens in the master and singles in the other bedrooms). The beds were extremely comfortable with thick, soft comforters and pillows. The bedrooms had heavy (new and attractive) drapes that blocked out the morning sun (wife and daughter tend to sleep in on vacation especially when dealing with time change). Apartment had 4 flat screen tv's and internet access (for an additional fee). We requested an apartment with a clothes washer (apparently not all have them) which was handy (none of the apartments have dryers however, just a metal rack to hang clothes on that worked out suprisingly well). No microwave but we didn't miss it. Daily maid service with clean towels (they did a great job daily). When we checked in, kichen had welcome basket with jams, tea bags, cookies, cereal etc. Also, when we got back to the apartment on Good Friday evening, there were 3 large chocolate Easter eggs in the kitchen (our kids were thrilled; it was a nice touch by the staff). Building has a number of small shops in it including a small grocery store, coffee shop, dry cleaner, liquor store, newspaper shop, fruit/vegatable shop, etc. Also, there is a restaurant and an indoor pool/workout facility. Neighborhood was extremely quiet (in a good way). No major groceries stores around that we could find but enough small groceries around. We initially had some concerns that we would be too far out from the major tourist attractions but that was not the case. Short walk (3 minutes?) to Pimlico tube stop. Only one stop to Vicoria station (very convenient). We walked to Buckingham Palace from the apartment on the morning we went to see the changing of the guards without any problem. Also walked home from Big Ben/Westminster area several times. Hope this helps. Let me know if you want more info.

Thanks to Sapjja for your detailed report.

The Citadine in Holborne is a great option too. It's less than a minute from the tube or you can walk to the city or Covent Garden in less than 10 minutes most. Great safe area with shops ect.!! I loved the area!!!