Michael and Phillip both make good points. This is something that you should discuss in detail with your advisor. Generally speaking, fees can be negotiated. Cost is always a major factor to consider and it will partly depend on which custodian is being used, size of the account, and who is managing the account. Pay careful attention to the transaction costs and who pays for them.
Tunc made the most important consideration - consider age and access to the funds. There are enough places to open an IRA with no annual account fee that your advisor shouldn't recommend a custodian that charges them.
All the best,
Jeremy M. Shafer, CFP®
While you will pay another fee for the additional IRA, I'm a big believer in having both spouses having IRAs. In your case, your wife will be more involved when she has her own account, especially if she hasn't been involved in the finances before this. This can put her in a better position to carry on if you predecease her.
Ideally you max out both Roth IRAs but in a world with limited resources that's not always possible. There is not a big difference in one Roth versus two just make sure your beneficiaries are set how you want them.
Also, I disagree with Michael as there should be no additional fee for a second IRA. If there is I would suggest finding a different advisor.
I'd say whatever keeps the peace in the house! No seriously, it may be easier just to have one account, in terms of brokerage and trading fees. It should be minimal, but why pay the additional fees for a second account if you don't need too.
I would also add this. The roth IRA becomes eligible for withdrawal after age 59.5. If there is a large age difference, it may benefit to plan for withdrawals now. If one spouse is 50 and the other one is 30, you can fund the 50 year old for the next 10 years and then fund the other spouse for the next 20 years. This will give you the option to withdraw the Roth IRA in case you need money. You won't receive this benefit if you split the Roth IRA's. The benefit does not work out if both of you are the same age.