I would not fly transpac in Eco, even on a relatively good airline like CX.
Here are some of the fares (without knowing your travel dates this might be off, but it gives you some idea) without taxes and other fines, first to HKT and then to BKK (often cheaper to buy a separate ticket from there)
[KVS Availability Tool 7.2.3/Diamond - Fares/PSH/RU]
Code:
BWI Baltimore/Washington Thurgood Marshall MD US [KBWI]
HKT Phuket Intl TH [VTSP]
R/T 05 Nov 2013 | Business
Carrier From To Fare Cur AdvanceP Min Max Fare Basis | Travel Period
--------- ------ ---- -------- ---- -------- --- --- --------------------------
HU BWI HKT 2136 USD 60 Days 180 IA6M5US4 07 May-31 Dec
MH BWI HKT 2645 USD *** 90 ZBT3MUS 07 May-31 Dec
CI BWI HKT 2782 USD *** 360 BC1YE 07 May-31 Dec
HU BWI HKT 2848 USD 14 Days 180 IA6M5US2 22 Oct-05 Nov
CI BWI HKT 2904 USD *** 360 BC1Y 22 Oct-05 Nov
HU BWI HKT 3713 USD 30 Days 180 IAP6MUS4 01 Nov-31 Dec
HU BWI HKT 4120 USD 21 Days 180 IAP6MUS3 01 Nov-31 Dec
HU BWI HKT 4425 USD 14 Days 180 IAP6MUS2 01 Nov-31 Dec
HU BWI HKT 4679 USD 7 Days 180 IL6M5US1 01 Oct-29 Nov
HU BWI HKT 4730 USD 7 Days 180 IAP6MUS1 01 Nov-31 Dec
CA BWI HKT 4913 USD *** 3 90 ZSPLAS7 01 Nov-31 Dec
OZ BWI HKT 5096 USD *** YOXUG 01 Nov-31 Dec
HU BWI HKT 5137 USD *** 180 IPR6MUS 01 Jan-31 Dec
MU BWI HKT 5147 USD *** 180 I6MNBZ 01 Jan-31 Dec
JL BWI HKT 5282 USD 50 Days 7 360 XZX5LA7Y 01 Jan-31 Dec
MH BWI HKT 5368 USD *** 180 DBZ6MUS 01 Jan-31 Dec
HU BWI HKT 5391 USD *** 180 IL6M5US 01 Oct-29 Nov
OZ BWI HKT 5402 USD *** YOWUG 01 Oct-29 Nov
AA BWI HKT 5444 USD 50 Days 3 360 I1X5F4B1 01 Oct-29 Nov
HU BWI HKT 5747 USD 14 Days 360 DAPRTUS2 20 Aug-31 Dec
UA BWI HKT 5831 USD 50 Days 10 360 ZFXG1NMD 20 Aug-31 Dec
JL BWI HKT 5892 USD 50 Days 7 360 XZW5LA7Y 20 Aug-31 Dec
HU BWI HKT 6002 USD 14 Days DART5US2 15 Mar-31 Dec
AA BWI HKT 6055 USD 50 Days 3 360 I1Y5F4B1 15 Mar-31 Dec
[KVS Availability Tool 7.2.3/Diamond - Fares/PSH/RU]
Code:
BWI Baltimore/Washington Thurgood Marshall MD US [KBWI]
BKK Bangkok Metro / Suvarnabhumi Intl TH = BKK DMK [VTBS]
R/T 05 Nov 2013 | Business
Carrier From To Fare Cur AdvanceP Min Max Fare Basis | Travel Period
--------- ------ ---- -------- ---- -------- --- --- --------------------------
HU BWI BKK 2136 USD 60 Days 180 IA6M5US4 07 May-31 Dec
MH BWI BKK 2136 USD *** 90 ZBT3MUS 07 May-31 Dec
CI BWI BKK 2675 USD *** 360 BC1YE 07 May-31 Dec
CI BWI BKK 2797 USD *** 360 BC1Y 07 May-31 Dec
HU BWI BKK 2848 USD 14 Days 180 IA6M5US2 22 Oct-05 Nov
CA BWI BKK 3560 USD 7 Days JXAP7 22 Oct-05 Nov
HU BWI BKK 3713 USD 30 Days 180 IAP6MUS4 01 Nov-31 Dec
CA BWI BKK 3764 USD 7 Days JSAP7 01 Nov-31 Dec
CA BWI BKK 3764 USD 7 Days JWAP7 01 Nov-31 Dec
CA BWI BKK 3967 USD *** JXR 01 Nov-31 Dec
PR BWI BKK 3988 USD *** 180 IL3BCXU 21 Jul-05 Dec
HU BWI BKK 4120 USD 21 Days 180 IAP6MUS3 01 Nov-31 Dec
CA BWI BKK 4171 USD *** JSR 01 Nov-31 Dec
CA BWI BKK 4171 USD *** JWR 01 Nov-31 Dec
AY BWI BKK 4222 USD *** IFLEX2US 01 Nov-31 Dec
RJ BWI BKK 4303 USD *** 7 120 DEERTUS2 01 Nov-31 Dec
HU BWI BKK 4425 USD 14 Days 180 IAP6MUS2 01 Nov-31 Dec
OZ BWI BKK 4588 USD *** YOXUG 01 Nov-31 Dec
HU BWI BKK 4679 USD 7 Days 180 IL6M5US1 01 Oct-29 Nov
HU BWI BKK 4730 USD 7 Days 180 IAP6MUS1 01 Nov-31 Dec
EK BWI BKK 4848 USD 50 Days 7 360 IX50US1 01 Nov-31 Dec
JL BWI BKK 4875 USD 50 Days 7 360 XZX5LA7Y 01 Nov-31 Dec
OZ BWI BKK 4893 USD *** YOWUG 01 Nov-31 Dec
CA BWI BKK 4913 USD *** 3 90 ZSPLAS7 01 Nov-31 Dec
CA BWI BKK 5015 USD *** ZRBU 01 Nov-31 Dec