You could definitely go with wallpaper...it is certainly economical since you have such a small area to cover...but it may not give you the posh spa feel you desire...if you decide that having a nice luxurious print that serves as a focal point and inspiration for all of the accessories....you might consider something like this.
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http://fineartamerica.com/featured/cherry-blossoms-soft-pink-floral-sharon-cummings.html

Place matching nightstands on both sides of the bed and a pair of shabby chic lamps or a chandelier over the bed (not too low).

If you do go with a wallpaper, then I would go from floor to ceiling behind the bed, then cover the edges with a trim moulding painted in the same colour as the rest of the trim.

If you are set on one of the three wallpapers you presented, I say the first (emperors garden). It will look lovely behind the bed and go well with the taupe walls. Go with lovely linens, as mentioned, side tables (if you have space) and table lamps.

Yes, the first one, and for a monochromatic scheme, you could go with the silver or black.

Thanks for all your wonderful suggestions. I am really keen with the idea of side tables but which ones should info with? I can't seem to find quite the ' right' ones so to speak.any photos of some ideas? the paint colour on the wall is farrow and ball charleston grey and I don't want to change it. The reason I have some white patch is coz I ran out of paint haha. What about the window ? Blinds , curtains or both . I have a radiator and don't like curtains covering the radiator ( I don't like short curtains) any ideas?not sure I understand the suggestion about painting the trim...

Not too keen on the wall art as it s quite expensive to get an affordable piece at that size. Any alternate ideas on wallpaper are welcome.gp barker is £125 euros and I need 2 rolls do if anyone had ideas on cheaper wallpaper , please tell me. Ps: love the cream/brown room .

You could place double moulding to frame your wallpaper behind the bed and continue the theme by doing double moulding that you would paint out over the night tables as seen in the pic
PIC submit for REFERENCE only

Sheer netting may give you the charm you're looking for, and it's inexpensive. Fushia accents look amazing with the taupe/brown walls, too. Paint 2 side tables fushia and add some fushia pilows. (TerraceGallery's photo over the bed almost has that, too).

#1 wallpaper is lovely. Side tables can be 2nd hand pieces you find in your home, relative's home or 2nd hand shop, same for lamps.

For curtain, I am a fan of bamboo shades. They come in different colours & sizes & are very economical.

You are on the right path....carry on & let us see your end result.

Makena, instead of wallpaper behind your bed, gathered fabric on a rod behind the bed might be a cheaper solution than the wallpaper. Install a regular curtain rod or wide Continental rod about 2" below ceiling on the wall, then a rod-pocket curain with a 2" header would end up right to the ceiling. You wouldn't have to have it go to the floor, as your bed is going to cover most of the wall. You would want it to hang just below where the top of the mattress comes. If your ceilings are 8 feet, then your curtain would probably be not more than 6 feet (2 metres?) Two lengths of fabric should be enough width to make it really full when gathered. To figure the amount of fabric, take the length of the repeat and see how many repreats go into the length of the finished curtain, then add how ever many reapeats go into 36 inches (90 cms?), for your top and bottom hems. You could also add a half-metre for making some shams or throw pillows.

For the window, I would get a shade or blind for inside-mount on the window, then add stationary panels on each side of the window in a matching or coordinating fabric that you used for behind the bed.

Thanks for all the suggestions. After reading all the above suggestions. My current thoughts are:
1. Use the Songbirds wall paper and frame it with panelling/trim that comes just under the bed frame as Anne/Nancy suggested. That would make it cheaper as i would not need to paper the bottom part of the wall.
2. I will need to visit Ebay and see if i can find some used stools (Thanks Sharon) and just paint them or just go with a covered bedside table. I think i can get some matching fabric or perhaps pull one of the colours from the wallpaper.
3. I have posted more pictures of the other side of the room. It has white chest of drawers( IKEA Hemnes) but not sure they will fit if i implement the above changes .What do you all think? I could move them to another room and just have a chaise lounge with storage but those are expensive... Any ideas on other options that i can use? I love the idea of using pictures or mirrors over the bedside table so i will definitely use that.
4. @Sardoli. I love the chandelier idea!

a chaise would be a very nice touch in a guest room. Check out Wayfair online. I found a simple, fashionable one for $265 which I ordered for my MBR. If this room has a cupboard, you can find a small dresser which fits inside cupboard for guest to unpack their smaller items.....

Sharon, can you send me a link to that chaise please? Thanks

Here are a couple of night stands that would look nice. I like the white ones to match your trim. The dresser above should be centered on the wall and it would be nice to have a mirror above it for your guests.

Roman shades or white wood blinds would make the room look finished. Put a live vine in a planter on the dresser. Philadendron doesn't require much care or light. No fake plants or flowers.

@ Leelee. I love them! Simple and very classy

Caroline: not exactly the same but close: http://www.wayfair.com/TMS-Chaise-Lounge-66318BLK-TXR1087.html

this is the one I got - it has storage under seat: http://www.wayfair.com/TMS-Leena-Cotton-Chaise-Lounge-66320BGE-TXR1292.html

I have purchased several items from them. Great site, values & service.