Wireless dropout up to 70% & network ?

Hello,
I am looking for help defining a wireless dropout I am incurring.

Specs:
ISP: Spectrum (formerly Time Warner)
Gateway Router: TPLink 1043ND, broadcasting only N and on a channel not used by the neighbors. 20 MHz channel width. Firmware up to date. http://www.smallnetbuilder.com/wireless/wireless-reviews/31630-new-to-the-charts-tp-link-tl-wr1043nd-ultimate-wireless-n-gigabit-router

Speed: Ethernet connection to gateway router a reliable 105-120 Mbps d/l and 25-35 upload as per speedtest on a Win7 based desktop.

Other devices always on:
- Linksys E2500 (http://www.linksys.com/us/support-article?articleNum=14120 with DD-WRT rigged as a client bridge to provide internet connection to an XBOX and HD Homerun, and located in living room 1 room away from gateway router.

- 2 iphones (5 and 6) - turned on all the time, but when testing wireless d/l speeds their wireless was disabled.

Other devices only turned on for specific use and never simultaneously
- XBOX 360 connected via Ethernet to the Linksys Client Bridge in the room next to the gateway router
- XBOX 360S (has built in wireless N adapter, but can only receive 20 MHz channel width and not 40) located a floor above and 15 feet laterally from the gateway router.
- Laptop (Dell Vostro 3500 turned on only for speedtests and has upgraded N wireless card)
- HD Homerun HDHR3. Ethernet connected to the Linksys. Internal network d/l speeds read in the low teens, but that may be a limitation of the device itself.

Speed results (tests repeated min 5 times per location and at different times of day):
Laptop connected wirelessly in Living room: 35-40 d/l, 10-15 u/l per speedtest.net.
Laptop connected wirelessly a floor above gateway: 30-34 d/l, 15-23 u/l
Laptop connected via Ethernet to the Linksys Client Bridge in living room 15-20 d/l, 9-12 u/l per speedtest.net
Laptop connected via Ethernet to Linksys E2500 (moved it up there for testing only): 20-26 d/l, 10-12 u/l
XBOX 360 connected via Ethernet to the Linksys Client Bridge in living room: 12-15 d/l, 9-12 u/l, per XBOX's network assessment
XBOX 360S upstairs (wireless): 21 d/l, 6-13 u/l
XBOX 360S upstairs via Ethernet to Linksys E2500 (moved router up there for testing only): 20 d/l, 8-10 u/l
** The network tuner graph on both XBOXs in both locations show 1-3 second drops in d/l speeds from the numbers quoted above to less than 10.

In addition, I have a TP-Link/Archer C50 router that I haven't opened yet. It is a dual band AC1200 router but it is only 10/100. I'm thinking about selling it vice using it to replace the E2500 as I don't have any devices that can accept ac and I don't want to use it to replace my gateway because it isn't gigabit...and I'm sure there are similarly priced ones out there that do have Gigabit. Anyway, I'm open to suggestions on what I should do with it.

Any thoughts on the culprit of the excessive wireless loss and/or a better router configuration with my current equipment would be greatly appreciated.
Thanks!!!